Minergate and Hitbtc are on the one branch
Democats and Poloniex are on the other.
The Bytecoin v1.0.11 daemon syncs to the Democats (and poloniex) blockchain.
Edit: the fork block:
http://democats.org/blockchain/block/?name=bytecoin&hash=1185958
https://minergate.com/blockchain/bcn/block/1185958
Most likely this happened as some of the services still did not manage to upgrade the software. Bytecoin released a new version in the very beginning of January, and we notified every single service by e-mail that the upgrade is crucial to keep everything going like clockwork.
Minergate is currently using the right chain, while Democats should upgrade their software at its earliest.
It can be quite tricky to get some exchanges to upgrade their wallets - been having some similar issues with IXC - some are still on a 5 year old version.