Question: Is there a way to achieve exporting the entire active records in a rails application to csv where each relation is a sheet of csv or there is another way to export full db data.Any suggestions?

Answer: 
I know I'm a bit late but since the answer for this matter did not work for me, here is how I solved it:

First of all, it's obviously a NuGet packages problem, so I searched in my .nuget folder at C:\Users{yourUser}.nuget\packages and looked inside some of the folders, in my case the Android support libraries folders, and saw that there were folders for many versions of that library excetp for the one I was referencing in my project wich was 28.0.0.3, the last version at this moment, the newest I had in the folder was for 28.0.0.1 so instead un uninstalling and installing everything again I just modified the android.csproj, changed the referenced versions for the support libraries for 28.0.0.1 and then it gave another error, I just literally downgraded some other libraries to 28.0.0.1 from Visual Studio NuGet package manager and then everything worked fine. 
Have a nice one. It took weeks for me of trying to find out.
Neither of the above solutions worked for me. I encountered the error opening an Xamarin project that was created in VS 2015 on VS 2019. I changed the "Compile using android version" in the manifest to Android 9.0, updated the NuGet packages, but this error remained. I also attempted the tried-and-true deleting ".vs", "bin" and "obj" folders.

What finally got rid of the "Program type already present: android.support.annotation.PluralsRes" error was deleting everything in the "Packages" folder for the project. My understanding is that directory was eliminated in VS 2017, but suppose because the original project was VS 2015 it was still being utilized and causing the conflict.