Thanks, Marcia Beloved, every experience is unique and stands on its foundation of reality in this vast existence. And we are putting them into a readable format in this dimension for benefit of ourselves and others, it will be guiding posts!

Regarding the advaiti and dwaitic. Let me elucidate a little bit about it.

There are six schools of philosophy in Hinduism (in India):

1. Sankhya/ Dvaita (Dualism)
2. Yoga
3. Vedanta/ Advaita (Non-Dualism)
4. Nyaya
5. Vaisheshika
6. Mimamsa

These 6 schools become 3 or multiply into 12, based on amalgamations of philosophies, or each one break into even smaller schools. But usually, these schools are classified as shad-darśana (Six-philosophies/ perspectives/ viewpoints).

There is one more division among them āstika and nāstika philosophies which literally means Āstika (Sanskrit: आस्तिक; from Sanskrit: asti, 'there is, there exists', believes in Self) and Nāstika (Sanskrit: na, 'not' + āstika, does not believe in self).

So, all 6 schools listedabove can exist in 2 divisions based on the belief of self, so 2x6 = 12.

There can be even more permutations and combinations like 2 x 6 x 5 = 60 schools like Astika-Dvaita-Advaita (Dvaitadvaita).

That's an overview of schools in Hinduism and the potential for multiplicity just like several schools in Buddhism like Theravada, Mahayana, Vajrayana, etc.

Advaita Vedanta (Non-Dualism) :

By 8th century CE, all of the Indian sub-continent (Thailand, Sri Lanka, Burma, Indonesia) was filled with Buddhist schools, and Vedic and Hindu schools were in decline mode.

Adi Shankara (700-750? CE) was born in Southern India and he changed the entire spiritual landscape of India. He lived only 30-35 years, exact dates are missing but nevertheless, his works are today's foundation of all Advaitic/ Vedantic Schools like Swami Vivekananda, Ramakrishna Math, and several modern organizations.

He vigorously debated Buddhist scholars on the existence of self and other subjects and by winning the debates all over India, he quite literally drove Buddhism to the corners and brought back the main school Hinduism and Vedas. It is an irony that a great saint like Gautama Buddha was born in India but there is no Buddhism left in India.(I meant mainstream)

The legend says Adi Shankara was one of the Rudras, he left the energy behind in India to block the Buddhism spread and drove Advaita Vedanta to its peaks. The energy is still running very high. He reinvigorated the old and lost Advaita Vedanta into new heights from 750 AD.

Advaita (Non-Dualist): Not to be confused with non-dualism mentioned in Bhagavad Gita (which is Sankhya texts), here the non-dualism is there are no 2 categories of Atma i.e. Jivatama (Limited Being) and Parmatma (Ultimate being), there is only one transcendental atma (self).

So, the Advaita Vedanta school believes in Core-Self and says all Core-self are the same and ultimately merge into Brahman Effulgence and be permanently there, there is no way back. There is a bandwidth within Advaita too, some become atheistic, theistic, knowledge-based, yoga-based, etc.

In non-duality, there are no limited individual souls (Jivatman), and there are no separate unlimited cosmic soul (Paramatma). All souls and their existence across space and time are considered to be the same oneness. Spiritual liberation in Advaita is the full comprehension and realization of oneness, that one's unchanging Atman (soul) is the same as the Atman in everyone else, as well as being identical to Brahman (this para taken from Wikipedia)

The cosmic consciousness experience I had is from this transcendental reality more accurately described in Advaita (as mentioned above)

That's a basic overview of Advaita (Non-dualist school)

Sankhya-Dvaita (Dualism):

Sankhya-Dvaita has been there even for a very long time and even Krishna spoke about it in Gita. Again with the advent of Buddhism, almost all schools of Hinduism were running dry, with Adi Shankara's Advent things started changing and Hinduism schools were slowly striving again but Advaita-Vedanta was the superstar among the schools in terms of popularity and reach to the masses. Adi Sankara set 4 Math or Bases in 4 directions of India and placed is 4 supreme disciples and they were running the Math Lineage to peaks for several centuries, even today the math (Base) in all 4 directions are very powerful in terms of power and fame (at times, they faced some downs too but mainly ups), Swami Rama (a great yogi) also served as Acharya briefly in one of the Shankara Math (Base).

So, now it is a Herculean task for anyone who comes later to steer the momentum in Dvaita (Dualist) direction. Around 1200 AD, Madhvacharya was also born in southern India and went to learn the Sankhya philosopy from Vyasa in Himalayas. He was the feircest critic of Advaita (Non-Dualism) and Shankara Works.

He reinvigorated the Sankhya- Dualist School of philosophy and single-handedly bought the Sankhya-Dvaita to the mainstream, which was a big task back in the day when Advaita was ruling every street. He won several debates all over India with Advaities and established Math or Bases to take forward the Maddhva lineage of Sankhya philosophy. He is also considered one of the Vayu Deities (Air or wind).

Dwaita declares there are two types of self: Jivaatma (limited-beings) and Parama-atma (Ultimate Being). 

Purusha (Subtle body, core-self + adjuncts) of Jivatmas is bonded to Prakriti (Subtle Material Nature). The human experience is an interplay of Purusha-Prakriti, Purusha being conscious of the various combinations of cognitive activities. The end of the bondage of Purusha to Prakriti is called liberation or Kaivalya (Isolation) by the Sankhya school. (this para was taken from Wikipedia)

That's another brief overview of Madhvacharya and Dvaita's school of philosophy.

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Now coming to my statement of changing sides from Dvaita to Advaita to Dvaita, (haha, such a long preview before answering your simple question, sorry for the length, your question demanded it):

Age 7 to 17: Dvaita (10 years, basic dvaitic training at child-teen level: Bhagavad Gita, Ramayana, Puranas)

Age 17 to 29: Advaita (12 years of Experiential learning of Advaita, several Transcendental Oneness experinces, Reading Upanishads, Adi Shankara's Works, Shivananda works)

Age 29 to until now: Dvaita (Studying higher level of Bhagvad Gita, Uddhava Gita, Ramayana, Puranas again)

I was like an alternating current between Dvaita and Advaita, not planned it just happened. I found myself in each camp and much later realized I was in the opposite camp. Both the camps are very accepting but the psyche struggles to accept the new camp instantaneously.

Two very opposing and quite inimical camps (cautiously stating it), so shifting between them is not a psychically easy task. Tectonic psychic forces are needed to push one from one side to another.  

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So, practically let me tell you about an incident, it could be funny now but I was spooked and scared:

When I first met Michael Beloved lot of things were unfolding (ups & downs), but after 2 days, during a evening while I was holding his book on Bhagvad Gita Kriya Yoga, I saw another name there "Madhvacharya".

When I read it, I read it as "Madhava-Acharya", Madhava is a common Vishnu or Krishna Name, so my mind read it that way. I was like okay, he is a vaishnavite and it is common to have a Vishnu name.

Michael Beloved then corrected me, it was not "Madhava", it is "Madhva"  and he said he got that name in an ashram from an acharya when he raised "2 fingers". (Remember in my cosmic consciousness post, I raised one finger after that experience [there is a symbolism to fingers here, that alternating energy is running over centuries]).

Seeing 2 fingers raised psychically unsettled me. I was like wait, you mean Dvaita proponent "Madhva" and he silently and cautiously nodded with that look he gives with an angle.

I got super spooked and I thought "Oh sh**, I have been super Advaiti all this time over a decade and I am sitting in front of a Dvaiti, I am going to get cursed and burned now".

I was rubbing my back on that patio chair cushion and my mouth froze and dry and taking a gulp of saliva into my throat, wondering what is going to befall me and unknowingly I entered this opposite camp without knowing the dangers, I wish I am spared today. (Today, I get chuckles when I type this, but I was spooked so badly that day)

But he was very kind and very understanding of my background. Advaiti schools inject a Dwaiti resistance energy into the psyche (vice-versa) and I struggled psychically for 10 months with lot of help from others to understand Dvaita and reconfigure my psyche.

It is a considerable struggle, it is not easy to overcome. I have to highlight this.

Ultimately, whichever path one is destined to seek salvation, one should quickly settle in that path and quickly reconfigure the psyche pertaining to that path or guru, no point in trying to salvage old glories or interjecting other systems into new systems.