OK, then is the following (in red) correct?, as I posted it was "as I read/interpreted the rules":
- Origional in WH and Prov in rough = Play 4th with Prov as against PD with origional so playing 3.
- Prov in WH and Origional in rough = Play 2nd with Origional.
- Orig. and Prov. in the rough = can't identify which is which = play 5th from the tee?
27-1. Stroke and Distance; Ball Out of Bounds; Ball Not Found Within Five Minutes

a. Proceeding Under Stroke and Distance
At any time, a player may, under penalty of one stroke, play a ball as nearly as possible at the spot from which the original ball was last played (see Rule
20-5), i.e., proceed under penalty of stroke and distance.
Except as otherwise provided in the
Rules, if a player makes a
stroke at a ball from the spot at which the original ball was last played, he is deemed to have proceeded under penalty of stroke and distance.

b. Ball Out of Bounds
If a ball is
out of bounds, the player must play a ball, under penalty of one stroke, as nearly as possible at the spot from which the original ball was last played (see Rule
20-5).

c. Ball Not Found Within Five Minutes
If a ball is
lost as a result of
not being found or identified as his by the player within five minutes after the player's
Side or his or their
caddies have begun to search for it, the player must play a ball, under penalty of one stroke, as nearly as possible at the spot from which the original ball was last played (see Rule
20-5).
OK, never mind...I just found this =>
27/11 Provisional Ball Not Distinguishable from Original Ball
A player entitled to play a provisional ball from the tee plays it into the same area as his original ball. The balls have identical markings and the player cannot distinguish between them. Following are various situations and the solutions, which are based on equity (Rule 1-4), when the above circumstances exist and one or both of the balls are found within a search of five minutes:
Solution 4: One could argue that both balls are lost.
However, it would be inequitable to require the player to return to the tee, playing 5, when the player has found both balls but does not know which is the original and which the provisional. Accordingly, the player must select one of the balls, treat it as his provisional ball and abandon the other.