setSkipEqualMaterials of ImageRegularParametrisedVolume setting to zero causing system to complaining geometry overlapping

[tontyoutoure]

Describe the bug
ImageRegularParametrisedVolume cannot be run with setSkipEqualMaterials set to 0, which is the default setting of the example:

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
      issued by : G4Navigator::ComputeStep()
Stuck Track: potential geometry or navigation problem.
  Track stuck, not moving for 10 steps.
  Current  phys volume: 'mouse_physVol'
   - at position : (8.546886770821516,12.0804840530017,-8.4)
     in direction: (0.5022826066187168,0.7099447064248754,-0.4936503792236008)
    (local position: (0.04688677082151571,-0.01951594699830572,-0.09999999999999964))
    (local direction: (0.5022826066187168,0.7099447064248754,-0.4936503792236008)).
  Previous phys volume: 'mouse_physVol'

  Likely geometry overlap - else navigation problem !
   *** Trying to get *unstuck* using a push - expanding step to 1e-07 (mm) ...       Potential overlap in geometry !

*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

Desktop (please complete the following information):

• Gate version or commit hash: quite new, b88f722

Minimal example
GateContrib/dosimetry/dosimetry/molecular-therapy-I131
change interfile to image and iff to mhd in source131I.mac to make it runnable

Expected behavior
run without problem

Additional context
ImageNestedParametrisedVolume or ImageRegularParametrisedVolume with setSkipEqualMaterials 1 works fine, so not a big deal maybe.