Helm Installation fails with shared config maps
Couple of possible solutions:

Control the configmap from a third chart and add the third chart as a dependency in both the charts. This will duplicate the secret and can cause a skew in the values being used both the charts since if they have independent release cycles
Create the configmap in one namespace and refer to it using an external reference. You can see several examples of such at https://github.com/helm/charts/search?q=existingSecret&amp;type=code

I personally prefer option 1 since there is explicit dependency specification and gives the ability to deploy the charts individually