Price table alters itself, preventing multiple price tables

How to reproduce:
* Add 2 price tables
* and a rule that sets price by either depending on a user role
* want to show *both* tables

Expected:
* See both tables correctly

Experienced:
* Both tables contain the applied price table's content

Root cause:
commerce_price_table_field_formatter_view() applies the commerce_product_calculate_sell_price event to each table item, which in fact overwrites the one table with the other.

Solution:
The price application rule has no info to tell the real price from the table prices, so prevent applying price table onto table prices by hidden marker.