Roger Linn still owns the copyright to the sounds used on the LinnDrum. The original hardware patent has expired (after 20 years) and anyone can legally make an exact copy of that, but the trademark and copyright laws are different.
According to Behringer themselves they took the samples from the LM1, LM2 and LM9000 machines. Roger owns the copyright to these but doesn’t seem too bothered about enforcing his ownership rights, he explains it all in his essay here: lmdrum
Roger would still be within his rights (if he so chose) to enforce these rights and Behringer would have to licence the sounds from him, or if they did not come to an agreement they would have to remove the sounds/stop selling the machine.
We were having a discussion about this in the LMDrum thread and if Bruce Forat (who bought the Linn Electronics company assets) owned the copyright to the sounds, etc., but I emailed Roger to confirm.
See original comment below: