Simply put, no there was never a discussion like this that took hold on the national stage during the prelude to the War for American Independence. Examinations into what abolitionists movements were like during this period and also looking into the opinions of separation from the U.K. in general reveal why this is so.

Throughout the 1760s and early 1770s, it was only an extreme minority of Americans who desired seperation from Great Britain. During revolts to policies like the Stamp Act or the Intolerable Acts, the goal was always reconciliation and gain mutual respect between the two nations. There were many percieved benifits to staying under the control of Great Britain, mostly economical and militaristic benifits that strongly benifited the 13 colonies. This is why most Americans, especially the majority of the landed gentry sought every possible solution to reconciliation with the British Empire.

The majority of gentry supported policies like The Olive Branch Petition even after hostilities had broken out between the colonies and the empire. So by the time 1776 roled around and they realized that war was an inevitability, only then did majority support for independence happen. Few founders were like John Adams, who seemed to want separation from Great Britain consistently through this period. By the time they recognized that war was inevitable, they bonded together since there was no way that they could achieve anything without working together. It's also worth noting that the original idea for "America" is that there would be 13 different countries or states (country is a synonym for states) that would have loose affiliation with one another. This was outlined under the terms of the Articles of Confederation (drafted in 1776, became governing model in 1777, endorsed in 1780). It was not until the creation of a strong central government through the U.S. Constitution that the idea of one strong united country came about.

Abolitionist movements were not that large in the 1770s and held very little political power. Certain groups, like Quakers, consistently moved to push Abolitionist causes through this period, but they were a minority. In fact, every state allowed slavery in 1776. Only two, Vermont (which wasn't even a state yet in 1776) and Massachusetts had systems in place that granted freedom to slaves by the end of the American Revolution. So dividing two nations between slave/free would make no sense since every state practiced legal slavery.

There was not a discussion around creating two nations out of the American colonies because every state was a slave state in 1776. And because most founders were reluctant to go to war from the start, they suddenly found themselves as reluctant separatists who realized that if they were going to separate from Great Britain, they would need each other. That's why it was drastically important that all states work together when they decided to formally declare their independence.