When you choose reroll all enchantments in Modify tab, it can happen that number of them will decrease :)
I have faced it with Archeotech relic which is a damn pity case, was good item after all. My tests with green item showed that it's a high chance to get less number of enchantments after reroll all.
SO as a warning to others - think twice before doing that.
I have checked compendium about reroll and nothing is said about it, so looks like a bug.
So was 1
Got 2, than it was random number from 1 to 2 (never 3 which is max for module if its not relic)
No warning about the matter :)