COB non-duplication

So a buddy and I have been going back and forth on a question about COB non-duplication . We came up with an example but then realized we both came up with different outcomes and couldn’t decide what the correct one was.

Example:

A subscriber has 2 insurance policies and they cover as follows

Policy A: Co-ins 70/30 Deductible $200

Policy B: Co-ins 80/20 No deductible

On a claim that has an allowed amount of $300, policy A would pay as primary the following way

Subs pays deductible: $200 Policy A pays $70 Subs pays $30

If Policy B were primary it would pay the following way, same allowed amount of $300

Policy B pays $240 Subs pays $60

Now putting it together with both plans

If policy A is primary and Policy B is secondary, then

Policy A would pay $70 Since the subscriber is left with a deductible ($200) and co-insurance ($30) I think Policy A would push $230 to Policy B, at which point policy B would only pay the difference of the allowed amount ($240) and the total amount left over that Policy A did not pay ($230) so I say Policy B would only pay $10

My friend says that since the Subs needs to pay the deductible of $200 for Policy A then only the $30 gets pushed to Policy B, at which point Policy B would pay $210

Can anyone help me out and figuring what is the correct calculation

Thank you