I'll be preparing the initial fiscal year and the final (short year) returns for an estate in 2019. The estate will have been open 16 months and both of the ending dates will be 2019, can I efile both or must I paper file the 2nd one?
It does depend on the software provider, though. I use Drake software for 1041 returns, and they prevented the second one from being efiled because it was a "duplicate".
Most tax prep software will prevent a second e-file for the same tax ID # and year and same form. In MA you can file an amended return directly on their website.