There are few possible ways to try overcome the issue:
No make the second area as an exact copy of the first one. It could done manually or by Symmetry command (the second way could better).
To use transfinite type mesh. It will work, but it is not well for your geometry.
To make a mesh for one region and then to mirror it similar, as in the example mirror-mesh.py for python.
Do not hesistate to ask you question in Gmsh forum https://gitlab.onelab.info/gmsh/gmsh/issues.