https://www.augur.net/blog/v2-launch/

TL;DR: Augur v2 launch is coming up and will introduce a new REP token.  FF has requested all exchanges rename REP to REPv1 to avoid confusion.

Going forward, REP tokens will contain versioning in their name/symbol on chain so this should be a one-time "fix" for Augur v1 REP.