Will the same key come up twice in a row?

No. It works like a shuffled deck: you get every key once before the deck is reshuffled.

Which keys are included?

All twelve major keys, all twelve minor keys, or both, depending on your setting.

Stop practicing in the same three keys. Draw a random key, and every key comes up once before any repeats.

Will the same key come up twice in a row?: No. It works like a shuffled deck: you get every key once before the deck is reshuffled.
Which keys are included?: All twelve major keys, all twelve minor keys, or both, depending on your setting.

On a bench, the random key can set the key for your fretboard, circle of fifths and chord charts in one go.