In FCP select right click on your sequence, you will get a pop-up menu. Choose “Settings” which will open up a new window. What is the Frame size of both sequences? If they are different then that is your problem and why a 720p clip will come into a 1080 timeline small. It is easy to adjust them if they are wrong. You can fix one and paste the attributes to the other clips. Hope this helps and best of luck.
Stephen Smith
Utah Video Productions
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