Index of detected and custom interpreters are not unique

[karthiknadig]

Installed R version:
    [0] Microsoft R Open '3.4.1.1347 (Default)
    [0] MRO (Default)

when configured like this:

  "R": {
    "Interpreters": {
      "0": {
        "name": "MRO",
        "basePath": "/opt/microsoft/ropen/3.4.3/lib64/R"
      }
    }
  }