Currently, when OIDC is set to true, it does not allow you to use both AWS_ROLE_ARN (Role where Bitbucket has not been configured as a web identity provider) and AWS_OIDC_ROLE_ARN (Role where Bitbucket is configured as a web identity provider) variables in the AWS pipes. 

Error: An error occurred (InvalidIdentityToken) when calling the AssumeRoleWithWebIdentity operation: No OpenIDConnect provider found in your account for

There are use cases where AWS_OIDC_ROLE_ARN will generate temporary credentials, and the same will be used to assume a "function" role within the target account eg: AWS_ROLE_ARN.