I was playing a game of stronghold the other day and I realized that the mesmer was easy to spot out of his clones. He had just gotten supply and had the supply symbol over his head so every time he created a new clone I just looked for the little floating barrel. Needless to say he was not happy and rightfully so. I believe the best way to fix this is either
1) Disable the symbol for mesmers.
2) Put the symbol on all of the mesmers clones.
3) Disable the symbol for the entire enemy team.
Each of these three options has its ups and downs but they are in my opinion the best options.