Comparing text strings

[Rich Shepard]

I'm running Slackware64-14.2 and keep a list of installed packages. When a
package is upgraded I want to remove the earlier version, and I've not
before written a script like this. Could there be a module or tool that
already exists to do this? If not, which string function would be best
suited to the task?

Here's an example:
atftp-0.7.2-x86_64-2_SBo.tgz
atftp-0.7.4-x86_64-1_SBo.tgz

and there are others like this. I want the python3 script to remove the
first one. Tools like like 'find' or 'sort -u' won't work because while the
file name is the same the version or build numbers differ.

All suggestions welcome.

Rich