App roles as Entity alias

 We are using app role authentication and have created two roles one for reading secrets and other for writing secrets.  

   Created a app entity and put these two roles as alias for this entity.

  But whenever we generate new secret Id for a role it is creating a new entity even though a entity exists against these roles.

New entity is created only for the first time secret id is generated and for subsequent secret id generation for a role new entity is not created.

Does this entity remains for ever or only till the secret id expires.

Can any one help me why this is happening.
Does it really make sense to map app roles to a entity