Position Being filled and Cancelled straight away. Demo Account

Dear Team,
On several occasions, my system has opened an order then immediately attempted to close the position with 15 milliseconds.  

01/04/2020 14:09:19.600 | → Order OID36017435 is FILLED at 1.09407, position PID20367190 closed (01/04/2020 14:09:19.310 UTC+0)
01/04/2020 14:09:19.366 | → Request to close position PID20367190 is ACCEPTED, order OID36017435 created (01/04/2020 14:09:19.098 UTC+0)
01/04/2020 14:09:18.866 | Request to close position PID20367190 is sent to server
01/04/2020 14:09:18.710 | → Limit order to SELL € 500k EURUSD OID36016133 is FILLED at 1.09406, position PID20367190 (01/04/2020 14:09:18.439 UTC+0)
01/04/2020 14:08:58.460 | → Failed to close position PID20367190 with error "POSITION_LOCKED"
01/04/2020 14:08:58.210 | → Order OID36017421 is FILLED at 1.09406, position PID20367190 closed (01/04/2020 14:08:57.944 UTC+0)
01/04/2020 14:08:57.975 | → Request to close position PID20367190 is ACCEPTED, order OID36017421 created (01/04/2020 14:08:57.712 UTC+0)
01/04/2020 14:08:57.475 | Request to close position PID20367190 is sent to server
01/04/2020 14:08:57.475 | Request to close position PID20367190 is sent to server
01/04/2020 14:08:57.460 | → Limit order OID36016133 to SELL € 500k EURUSD is PARTIALLY FILLED for € 100k at 1.09406, position PID20367190 (01/04/2020 14:08:57.193 UTC+0)
 

The account is a demo account ctid1412177.  Could you please advise?

Many thanks,