As stated in bug 77243, printing through CUPS with collate disabled will only print the 1 copy as if i hadnt changed the number of copies, but with collate enabled and copies set to 2, that works fine. Test in Linux Mint with 3.6, 4.1, 4.2 and 4.3b.
After further analysis, i see that it must be a problem with CUPS as i had mentioned in comment 14 of bug 77243.