How to Merge Thunderbird Junk Training in Two iMap Computers? (Merging Training.dat)

I'd be happy with an answer, but I offer a possible solution. Can someone tell me whether it will work? When more than one copy of an iMap account exists, there is a problem with Junk mail learning. Namely, the learning only occurs on the computer where the user declares mail to be Junk, not on other copies of the same iMap account. It has been suggested that Training.dat be copied from one account to another, but that wipes out any training that has occurred on the copies that receive the new Training.dat file. A merge is needed. So... Does THIS work? Go to the Junk folder and select all mail in it. Mark all the mail as Junk (seemingly redundantly). Unless Thunderbird makes a special case of NOT learning from marking mail as Junk when it already is, this ought to work, right?