I don't know if there are any different markings on the case. If you have the ability to remove the top cover, the BB has two transformers inside (instead of one) -- making it a true dual-mono design.
http://www.ebay.com/gds/Classic-Aragon-Amps-A-primer-/10000000001149810/g.html
If you haven't been the above page, it's a good primer on older Aragon amps.