Thank you macuser_22 -- I know you cannot combine basis and they should never be combined, but that is exactly what TurboTax did so it's clearly a bug. I was trying to correct my basis which was zero since TurboTax had dropped reporting the Form 8606s the last few years. I was using TurboTax's interview for non-deductible Traditional IRAs where it displays the Basis it has from the prior year's and asks you to revise it. If you do, it then asks you to provide an explanation in a line-by-line format with associated numbers. I did this and checked the Forms and I now had a new "Blank Form" with my entires. Then I did my Spouse's corrections and was surprised when the explanation entry form already had my entries in it. When I added a new entry for her it got added to the total. Note - that I did not have a 2017 contribution while she did, so she will have a form 8086 but I won't. I would be happy to repeat this error with someone from TurboTax if I could figure out how to reach them (email or phone).
