Seed generation passes when experiment name is duplicated

[btlechowski]

The generation seed job should fail, but it passes.

Then in the client the seed is not applied:

[27107:259:1109/120010.074659:VERBOSE1:processed_study.cc(98)] BraveSearchAdStudy has a repeated experiment name Enabled

cc @atuchin-m @tmancey @iambrianfung