Why is Rules reacting on Commerce Events multiple times and out of order?
Solved!

I had upgraded to PayPal WPP, but also left PayPal Express Checkout enabled.

This caused EC to not display where it normally does, i.e. on every page starting with the cart, but to only display on the Review page where other payment methods can be selected. However, the Rules events for EC were evaluated in their normal place in the process.

Thus the Events were being evaluated even though they had apparently not occurred.

The multiple evaluations of the Event "Calculating the price of a product" is normal.