it looks like your problem is down to a combination of target lag and the assist function in your macro. If the clones don't pick up the target change, they won't reset their macro and you will be out of sync

ok, why repeat the cast sequence?

does this work? (written in work)
Code:
/assist [noexist,dead] zite
/castsequence [harm,nodead,nochanneling] reset=combat/target/alt Mind Flay, Mind Blast, Smite, Mind Flay, Mind Blast
I have added the alt reset condition to give you a manual reset but it depends on what other stuff you do, you may want to change or remove it

target lag = the time it takes for the main to update the server with its target and then the clones to query this info from the server