If I have a limited ship between two other ships, both of which have Dedicated on them, can I Strain both of the Dedicated ships so that the limited ship can then reroll two defense dice?

No. Once per opportunity would kick in and only allow you to do it once.

11 minutes ago, Lyianx said:

No. Once per opportunity would kick in and only allow you to do it once.

But Once Per Opportunity applies to the ship whose effect this is: that is, the Dedicated ship, no the defender. I tend to think multiple ships with Dedicated could be applied to the same roll. There's probably been precedent set with Selfless.

Yup works fine. Each instance of Dediated can let you reroll a die.

Yes it can stake, BUT you cannot use it to re-roll the same die more than once.