Copy machines are not blueprint machines and they do introduce distortion. But the amount you are talking about is probably not significant (2mm maximum).

I don't think you've done anything wrong in copying the plans. It is always necessary to transfer the plan patterns to the actual boat building materials and patterns, such as the photocopies you made, are a perfectly acceptable way to do that. The license that you have purchased with the plans is probably to build one boat. So if you gave copies of the plans to someone else there might be a problem. But anything you do yourself in the process of building one boat is OK.