I'm also in this boat.  No amount of tinkering with "Client Info" tab and "Part-Year/Nonresident Info" tabs seems to get the result of full-year residency in 2 states.  In my case, client is domiciled in CA (with home & intent to return) but has a job (interim pastor) for at least a few years in Idaho, and has moved there and is renting.  Both CA (domicile) & ID (>270 days) will claim him as full-year resident.

So is it really Lacerte's position that I should file a Federal & State return under one 'client' ID, then copy to another client ID and produce a copy 'dummy' Federal return so I can generate a normal return on the other state?  That seems beyond clunky and like it would make a mess of income sources with differing source states.

If this is right, then I'd produce the following??

CLNTID01 = Fed + CA = W2 (CA), W2 (US), 1099-R (CA), 1099-R (CA), 1099-SSA (CA)

CLNTID02 = Fed + ID = W2 (US), W2 (ID), 1099-R (US), 1099-R (US), 1099-SSA (US)

I'll also have to manually override the "other state tax credit" on the "St. Taxes" tab to get it to populate?

Sounds like a good one for the feature dev queue. 

From a user experience perspective, this is tough (even if I get all the manual parts right).  This has implications for eSignature.  For printing & assembling.  For making PDF's.  For linking to SmartVault (or Doc mgmt something something).  For proforma to next year.  For organizers.  Any adjustment to one Federal needs to be replicated manually on the other.  Every step needs deeper focus.  And this will last for each year my client is in this situation.  Given how states are more concerned about claiming income, and how remote work has increased, these situations won't become more rare.

Ugh.  So, if anyone has a magic bullet on how to handle this I'm all ears.  Please consider this is my nomination for escalating "dual-residency capability" in the dev queue.