Why does shared teams not cut across two plans for capacity

[Scott Stephens]

I have shared teams across two plans.  The plans are not showing over allocation in capacity when using the same teams in the two plans.

• Shared Team 1 has 400 hours of capacity per sprint.
• Plan 1 has sprint 1 allocating 400 hours to this shared team
• Plan 2 has sprint 1 allocating 400 hours to this shared team

There is not any call out of over capacity between the two plans even though technical the team is now working 800 hours when you combine the two  plans for sprint 1