First of all, don't give a lot of credence to my reply. I know almost nothing about SQL. But...

In the unlikely event that I understand what you are doing here, it seems as though you are trying to overwrite the existing Ac_Trn.mdf file with data from the N'AC_Fli_Data backup. So it makes sense that you would

MOVE N'AC_Fli_Data' TO N'C:\SQL DATA\ASL\Ac_Trn.mdf',
MOVE N'AC_Fli_Log' TO N'C:\SQL DATA\ASL\Ac_Trn_log.ldf',

so I would go with the first version, the one that SQL Management Studio gave you.

Keep in mind that this is ignorance and guesswork speaking!

tanstaafl.