If I have two Ho-Oh EX in my discard pile and flip tails for "Rebirth", can I flip a second time?
You can flip once for each Ho-Oh EX in your discard pile, but each coin flip is treated individually.
Source: Dragons Exalted FAQ (2012-08-23), TPCi Rules Team (2012-08-23)

Relevant cards

Note: All applicable cards may not be listed below.
WOTCGH_12