Can I stop replication of create/drop index statement on one slave of Mysql 5.6?
I don't believe there is a way to ignore specific DDL (or any DDL?).  If creating an existing index, it should throw an error, which you should be able to ignore on your analytics-slave.  

Alternatively, don't replicate Index Creations.  

set log_bin=0; 
create index name on table;
set log_bin=1; 


Create a wrapper script to apply to master and slave as needed.