Alle vendor quotes are currently displayed in the order in which they are generated, irrespective of whether they actually apply or not.

Example:

I have a workflow where the Translation task is assigned to Vendor Order Template A by default. The workflow also comprises a Project Planning step which allows project managers to change the assignment of the Translate step.

When a project manager changes the assignment of the Translate task to a different Vendor Order Template, Trados Enterprise will automatically generate a new Vendor Quote for the new Vendor Order Template.

The issue here is that the previously generated Vendor Quote is still available in the project under Costs -> Vendor Quotes and is always pre-selected by default even though it does not apply to the project anymore. 

As this could lead to confusion, I would suggest that only the latest Vendor Quotes that are applicable to the project (i.e., that correspond to the actual task assignment in the project) be shown and that any outdated Vendor Quotes be hidden in the UI, maybe with an option to have them displayed if needed.