My friend mentioned Linkify may be causing the "IQ9" signature thingy, it overrides someone's actual signature when Linkify loads onto the page. It isn't consistent though, however I tried disabling Linkify and IQ9 wasn't appearing at all for me, it may have just been chance..
The following quote leads to someone's post where IQ9 was appearing occasionally for me, doesn't seem to affect everyone's signature
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Haven't checked just yet, but could potentially be something to do with certain (/any?) colours used in the signature, or a certain character, not sure
E: Doesn't matter if thread is locked or not
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E2: Colour is irrelevant, saw it happen with Singularity's post which is just a centred ".", so maybe its BB codes interfering somehow