Here is a link to a used copy of Modena 10 (with certificate) currently for sale on HipStamp: https://www.hipstamp.com/listing/mo...ert/20698345
If you search HipStamp for "Modena 10", you can also see a forgery, offered as genuine, for $292.50. Obviously it is not worth that.
Some of the points to look for:
1. Genuine stamps have a period after the numeral of value.
2. On genuine stamps, the "C" of CENTS has a serif at the bottom.
3. On genuine stamps there are 5 vertical lines in each of the upper quadrants of the shield, and 6 vertical lines in each of the lower quadrants.
4. On genuine stamps, and some forgeries, the line under the value in the bottom panel does not connect to the squares at either corner.
All the stamps of Modena were forged multiple times, by different forgers, but my off-hand opinion is that yours is genuine. Congrats!