At least you are flying CPH-ARN-PEK-CPH, which means that your original booking doesn't fly CPH-PEK, only on the way back. Mine is crazy, I'll be joining CPH-IAD and back, plus 4 absolutely unnecessary legs (Mr. is driving to DK to work so we don't pay much for crossing the bridge) - MMX-ARN, ARN-CPH and back. Don't ever expect me to pay emission compensation and don't tell me airlines try to go green - they are certainly not green and they really want me to get the extra 1000 miles.
Also I'm shocked that there are 2 departures ex-MMX in the morning with 45 minutes interval (6:30 and 7:10) also the ARN-CPH too (9:20 and 10am). Wonder if they would cancel the earlier departure if they can merge into 1 flight.