confusing isc-dhcp publishing history in Debian

In attempting to resolve LP: #1597414, I spent some time examining: https://launchpad.net/debian/+source/isc-dhcp/+publishinghistory.

I would like to verify the Launchpad import of the Debian history is correct. In particular, for Sid, I see:

...
4.2.2.dfsg.1-3
4.2.2.dfsg.1-4
4.2.2.dfsg.1-5
4.2.4-1
4.2.4-2
4.2.4-3
4.2.4-4
4.2.2.dfsg.1-5
4.2.2.dfsg.1-5+deb70u2
4.2.4-5
4.2.4-6
4.2.2.dfsg.1-5+deb70u3
4.2.4-7
4.2.2.dfsg.1-5+deb70u6
...

Not only does the versioning not increase monotonically (which we can work around in our importer by manual override), but the same version was published twice (4.2.2.dfgs.1-5). The latter case is much harder for us to handle (without some redesign), as we assume a version is only published once in a given series/pocket. We could include the publishing date information, but I wanted to confirm what sort of assumptions I can make in the importer code re