Is there a restriction when using the same secret in two repositories?

I have two repos that push to a custom repo. Using the same CLI for add secret I am adding docker_username and docker_password. One completes and the other fails but I cannot discern why. They have the same drone.yaml and the same credentials.

Is there a restriction when using the same secret in two repositories?

nope

we use the same docker username/password to publish 100+ images, including drone, and all the drone plugins. I recommend posting more details, including a sample yaml configuration file.