Axiom has been using this technique for many years. I have a pair of AX3 (circa 1990) that have this. I recently posted a question to Ian asking if this was still in practice, and here is a direct quote:
"Both the M60s and the M80s have the separate internal cabinets. The dual 6 1/2" woofers are also crossed over to act like sub-woofers similar to the old AX3s and AX5s. This is the best way to get the advantages of both a two-way system and a three-way system without the compromises inherent in each."
Regards,
BBIBH