It is really hard to say. It certainly isn't impossible and if we went by looks alone, it would even seem likely. But looks can be so deceiving when it comes to sheds.
I remember seeing a huge buck that was mounted on the wall of an outfitters. Below it was a collection of sheds. One of the sheds matched the buck on the wall in every way shape and form so I made the comment that the particular matching shed obviously belonged to the buck on the wall. The outfitter looked at me and grinned. Come to find out the shed was from a completely different county and couldn't have come from the mounted buck. Boy did I feel stupid.
Did you save the jaw bone to age your buck? You say that you found the shed 3 years ago? Could we make an educated guess and say that the youngest that buck could have been at that time was around 2 1/2. That would make him 5 1/2 or six years old now. If that shed was from a 3 1/2 year old deer then the deer would be 6 1/2 or 7 years old now. What is the potential for deer in your area antler wise? I know here even if the genetics aren't the best in terms of tine length the horns get really thick, lots of mass on anything over four years old. A deer 5 1/2 to six years old would carry huge mass as would a 6 1/2 or 7. In addition, it is rare that one comes across a deer that age in the wild, albeit, it is not an impossibility. At any rate if you could get a cross section of the tooth done to age the deer it would help in your quest to answer your question.
Also, I am told now that there is a DNA test that can be done to see if it is the same buck. How much money do you want to spend finding out
. I have a feeling that would be expensive, but then you would have a definitive answer.
To say it is or to say it isn't the shed of your buck would only be a guess.