Hi from NRW to NRW,
I'd like to add a bit to jcl's comments: please be aware that Z12 is a set of multiple algos, all running independently. So virtual hedging is the only option to limit opposite positions by different algos.
And as I have some experience with Z12 trading an IG (not IB) account (recently extremely profitable, by the way) I can safely state that executions as you are listing them here are not the normal Z12 behaviour. I guess it somehow relates to the fact that your orders are handled as "Odd Lot FX Transactions" (see https://ibkr.info/node/1459). The pattern looks as if the above are actually 3 Z12 trades only (and my Z12 on IG did very similar trades today: GBPUSD long, EURUSD long, USDCAD short) - somehow wildly split into pieces bei either IB, the API, or the Zorro IB Plugin. I'd further investigate into this direction (if you really want to trade Z12 with IB which is not recommended!).