Duplicate Golem Bug

I'm assuming this is on your witch character.
In your helm, you have Summon Chaos Golem supported by Cast When Damage Taken, so it will trigger, summoning a new chaos golem and replacing your oldest golem if this would put you above the limit.
This gems is just within the required level range your CwDT can support (your Summon Chaos Golem gem requires level 42, and your CwDT gem can support gems requiring level 42 or below). So it might be that previously this was unsupported and has only started since you levelled up the CwDT support.