The context here is that the box in question was running a beta version of Debian. A version of collectd was built and installed. The box was then upgraded via apt-get to the released version of Debian, which changed the tpkg OS value from "Debian-testing" to "Debian-7". While that understandably leaves tpkg in a bit of a mess, there's no reason that referring to the installed collectd package by the bare package name shouldn't continue to work.
jheiss@office:~> tpkg -r collectd
No matching packages
jheiss@office:~> tpkg -r collectd-5.1.1-1-debiantesting-armv6l.tpkg
The following packages will be removed:
collectd-5.1.1-1-debiantesting-armv6l.tpkg
Confirm? [Y/n]
The context here is that the box in question was running a beta version of Debian. A version of collectd was built and installed. The box was then upgraded via apt-get to the released version of Debian, which changed the tpkg OS value from "Debian-testing" to "Debian-7". While that understandably leaves tpkg in a bit of a mess, there's no reason that referring to the installed collectd package by the bare package name shouldn't continue to work.
jheiss@office:~> tpkg --qa collectd-5.1.1-1-debiantesting-armv6l.tpkg
jheiss@office:~> tpkg -r collectd No matching packages
jheiss@office:~> tpkg -r collectd-5.1.1-1-debiantesting-armv6l.tpkg The following packages will be removed: collectd-5.1.1-1-debiantesting-armv6l.tpkg Confirm? [Y/n]