That's not something that Phil would be able to confirm I believe, no disrespect intended, he's a computer techie and a very good one. I agree it's not as designated in the submission and is ngc4256. I know that's just a typo on your part Manuel.
A search on the coordinates submitted for the job do not match anything and are certainly not those for the intended target Ngc5906. A search in Aladdin reveals ngc4256 within the radius of the actual coordinates used, and Telescopius confirms it as ngc4256 showing as the exact position the galaxy appears in the data.
Not sure what can be done with this, maybe a corner crop to position the galaxy as a more pleasing composition, we don't have Ngc5906 however.