The version string for your modules is relative to the OpenERP "Series" on which they are supposed to run. The series number is made of the first 2 numbers of the full server version: e.g. 6.0.4 is series 6.0, 6.1.1 is series 6.1, 7.0.0, is series 7.0. The module version that is displayed in the module list is made by concatenating the server series number with the version string of each module. If your module had version "1.4" and was running on server "6.1.1" it would appear as version "6.1.1.4".

This number is certainly peculiar but mostly legacy and used as a shortcut to know both the series and module version (you can infer it by knowing that the first 2 numbers always represent the series)