Cross-Continent SQL High-Latency Data Synchronization
Duplicate keys with AUTO_INCREMENT are not "possible".  See auto_increment_increment, which must be set to 2.

In general M-M is problematic for a number of reasons, which I will not go into, especially if you write to both of them.  You are better off writing to only one of them, leaving the other as a hot failover server.

For pages that only need read access, have Slaves in both datacenters.

Have client machines in both both datacenters; have them hit the local Slave for reading (if it is not down).

But beware of the "critical read" problem.

Plan A:  Change user expectations so that they understand that writing may be slow.

Plan B:  Use NDB Cluster with its "eventual consistency" model of replication.  Caveat: There are a lot of differences between InnoDB and NDB.

A technique that may help:  If you need to send multiple queries to a 'remote' server, package them in a Stored Procedure so that there is only one cross-continent hop.  (This, of course, is not always possible.)