I've seen this cancel a few times, usually on higher-denomination third issue revenues. It's a circular handstamp with superimposed letters B and D in the form of a monogram.

Then last month I found the stamp below on
ebay, which caused me to do a bit of a double-take. It's a similar superimposed B and D, but in a different font and in a smaller format. While I've seen probably about a half dozen examples of the cancel above, this is the first time I've seen the small format handstamp, presumably from the same company.
Any ideas?
