Yes. The order should be cancelled.
If you are wanting help selecting memory for your system, then let us know.
For future reference, it is usually advisable to get memory in dual channel kits (with modules being the same capacity) where the modules have been tested for compatibility with each other. And maximum memory bandwidth then becomes available to the system in dual channel mode.
Trying to match individual memory modules (not from a dual channel kit) can be a problem due to variances in module characteristics.
Also, the P7H55M-LE together with the i7-780 only supports up to 4 GB memory modules anyway. So 8 GB modules will not work.
So, suggest looking at getting a 2 x 4 GB dual channel kit in the future.