"Glamours may not be stacked."

[lololink]

However, this is no longer possible now. If you try to repeat the process, you will get an error message of "Glamours may not be stack.".

TL;DR, you can't glamour a gear with another piece of glamoured gear.

As long as I remember this was never possible, first time I tried it said me that I had to remove the glamour in order to use the item for a glamour. Or maybe it was an overlooking at the very beginning of glamour that was fixed.