It's possible to add a printer to a billing model twice

[eduardomozart]

• Version of the plugin : 1.7.0

• Version of your GLPI : 9.5.2

• Steps to reproduce (which actions have you made) :

It's possible to add a printer to a billing model that it is already twice through the massive action "Printercounters - Set billing model".

• Expected result :

The plug-in should detect that the printer is already at the billing model selected and do not add it twice.

• Actual result :

Is shown "2" linked items at the billing model when in fact there's only one (SEC001599A9C2CE was added twice).

• URL of the page :

• Screenshot of the problem (if pertinent) :