What are two consecutive strikes in bowling called?

Answer 1

The differents names for two consecutive strikes are:
1. Double
2. Double bag
3. Double bagger."

Years ago there was an award given to junior bowlers who threw two in a row, it was called a "hambone."For more information see links below.

Answer 2

A Varipapa 300

I saw Jonh petragla bowl one of those. It is something marvelous to observe.

Answer 3

a Double.