Yes, but they are routine and are less of a concern than they would be if the Bitcoin algorithm was arbitrarily speeded up, Ethereum's proof-of-work is not merely bitcoin's with a faster blocktime.
The concern is that faster blocks imply a predictable increase in branching because of network latency, and consequently faster blocks leads to loss of hash power - network inefficiency.
GHOST - Greedy Heaviest Observed Subtree is a solution to the loss of hash power, first introduced in 2013 by Yonatan Sompolinsky1 and Aviv Zohar. https://eprint.iacr.org/2013/881.pdf
Ethereum doesn't implement GHOST exactly as described in that paper, but the original work is a good place to start exploring Ethereum's implementation.
Have a look here for details about the Ethereum implementation: https://github.com/ethereum/wiki/wiki/Design-Rationale#uncle-incentivization
Hope it helps.