It is not uncommon for construction bid projects to have alternate bid items as part of the design. Revit users will typically use the Design Option capability of Revit to show the alternate bid(s). This works excellent for the Architect, but it does not work quite as well for MEP consultants.
For the Architect to make it a bit easier for their MEP consultant, it is good for the Architect to create a model elements only view of the alternate bid design option in their Architectural model. This allows the MEP consultant to reference this view in their model without extraneous information.