Are you comparing it to the other valance or to the mounting holes on the fenders ? Pictures sure help. Too long and doesn't line up really don't tell us much.
Is it a small amount or a large amount? We can't see what you see. Even original factory sheetmetal sometimes needs to be fitted. No two cars are exactly alike.
Thanks. Much better with a picture. You say it is too long. How does the new panels' contour compare to the original valance? If it looks the same, the contour of the r/r fender may need work. If it looks different, the new panel will need work. Do you have much body/fender experience ? Has the car had possible repair to the fender in the past ?