What is the meaning of Double_up?

To double the quantity, amount or duration of something

To double one's amount of chips by winning an all-in pot.

To bend, bend over; to fold; to stoop.

To cause (someone) to bend over; to beat up (someone).

To have a secondary use.

To get the second out in a double play, typically referring to getting an out by beating a runner back to a base (often by throwing) after a fly ball has been caught

To employ double the usual resources for a particular purpose; to work in pairs.

To marry or live with someone; to share a living space.

Source: wiktionary.org