12Bid, ask and the cancellation gap

If the chart shows bid 1.1215 and ask 1.1216, a buy stop at 1.1218 may trigger when the ask reaches it, even if the bid stays below.

Verify your broker. One-cancels-other is an instruction, not a guarantee: it may be broker-side, platform-side or a script, and terminals disconnect. Demo test before unattended use.

What if both fill?

Treat it as an execution incident: cancel unfilled entries, flatten unexpected exposure, verify the position and order list, keep protective stops until closed, then pause and investigate.