Not really sure how you stand legally but morally it would be the wrong thing to do IMO. You would possibly receive a cease and desist notice from MTL but i don't think there has actually been a court case yet
that i am aware of as the threat usually puts most people off.
There is a possible court case brewing with the Easi entrie and Ansan machines as one manufacturer has had enough.
One stand at lockex was duplicating Evva EPS and did not think there was any issue in doing this, about 2 hours hours later the machine was removed from the stand as they where issued with a warning so we will have to wait and see what happens in the not to distant future as there may finally be a court case over patented keys and a ruling made which could well set a precedent for (maybe unlawful) duplication of key blanks.