Here is a scan with the evolution of Lattes townhall's franking machine, French commune in Hérault.
It reproduces the "Port Ariane" pictorial cancellation that Lattes-Center post office was using at that time.
The machine was changed between 2000 and 2002. The new one prints postal mark in two parts, asymetrical moves are possible like in March 2002. The color varies, certainly because the ink quality or disponiblity.
To know more about the postal sending of electoral card in France, you can read News du phospho blog's article posted 17 April 2007.