Ok and thank you for your answer.
My English is very poor and I apologies for that !!
Now test this :
Make a new concert from scratch , make a patch with two or three or four virtual instruments with the buttons , faders ( volumes sends eq comp etc etc etc....) ....assigned to the channels strips of this instruments and mapped to your midi controller
Now make an alias of this patch and make different adjustments of the same buttons and faders assigned to the channel strips.
Ok , this is fun and you can save the concert on your Mac and it is very functional , right ??
Now, quit MainStage and reopen it , and load the concert you have saved.
Bingo !!!! The mappings of the first patch are OK but the mappings of the alias are disappear !!!!! If you have changed the names of the mappings or the values or others settings, they are not reloaded and are not functional at all !!! This is a very large BUG!!!!!
I hope you can understand my explanations !!