Dust changes every two rounds

So i haven't played CS:GO in around two months, and today i thought i'd play again. I played on Dust 2, but every two rounds it'd switch to Dust 2, but it looks like 1.6 / CSS. First round normal, second one literally the 1.6 / CSS map copied, and it happened in deathmatch MM and with bots. Pretty sure i haven't seen this before, is it something new?