Are you in a supergroup and in supergroup mode? If so that may be your supergroup logo, which you can turn off as an option in your supergroup colours window.
Ah didn't consider that, and yes, joined one just to experience how it works, so its very likely you just answered my issue.
Many thanks. 
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If you are in an SG and in SG mode, their symbol will be on your chest. You can change it by going to your SG window, click the "Settings" button, then the "Accept" button and click on "Hide Super Group symbol"
Hope that helps!
Just got my 2nd costume slot, made the second costume, and have choosen a different chest icon for her symbol for each, however for some reason both appear as the Scales while in game.
It's bizarre as on the character select screen, the costumes are correct, however as soon as I login to the city, the Scales are there instead.
Anyone heard of that bug before, is there a fix?