When looking at packages on apt.puppetlabs.com, the majority of them do have the same version across distro releases, leading to this confusion:
For example, this means that updating from packages targeting wheezy to packages targeting jessie is weird, because the puppetlabs-release/jessie is the "same" version as puppetlabs-release/wheezy.
In a similar vein, single-pool repo mirroring tools, like reprepro, get confused by this.
A solution would be add the target release version into all package's versions. The current practice of putting the release name as is done with some of the PC1 packages (e.g. puppet-agent_1.3.5-1jessie_i386.deb; puppet-agent_1.3.5-1wheezy_i386.deb) is not sufficient, as the ordering for the names is not correct.
[This was reported to me by a Debian developer.]