add check for unique device ids

[nasnoisaac]

What does this PR do?

Fixes #8634

Check the uniqueness of gpu ids. The backend doesn't support duplicate GPU.

Does your PR introduce any breaking changes? If yes, please list them.

None

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[pep8speaks]

Hello @nasnoisaac! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-08-03 07:45:54 UTC

[codecov]

Codecov Report

Merging #8666 (7d3a525) into master (e5d9e21) will decrease coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #8666    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         167     167            
  Lines       14033   14037     +4     
=======================================
- Hits        13004   12453   -551     
- Misses       1029    1584   +555     

[carmocca]

Remember to update the CHANGELOG :)

[ananthsub]

thanks for adding this check @nasnoisaac !