1863 France Napoleon Stamp Sc#15 (Right Picture To Research) (Left Picture To Compare)

You can see 2 Napoleon stamp Sc#15 of 1863 issue. Both stamps was used in Alger. Right stamp has unusual broken print. Left stamp has good print and added for comparison only. Right stamp has different pattern from pattern of left ordinary stamp.
Could you please to identify stamp on right side .Is it Error print ? Or Is it Forgery to cheat postal services. Where can I find any information for this case ? Thanks for the aid. Second picture is enlarge image of right stamp.

Is not Sc#15 1854?

The stamp on the right is normal, just overinked to obscure details that appear on the left stamp. They printed many many thousands of stamps and perfection was not guaranteed. Look at the stamp and there are many other areas of overinking: under the chin, the back of the head, the bottom edge of the bottom tablet.

EDIT: If the cancel is 3710 (small numerals), then it was used from Alger/Algiers in Algeria. It might be 3716 instead (unknown town in Algeria).