Double up limits

[US 2]

I have made 2 visit s to a Michigan casino this year that still has machine where you can double up... luckily I've had handpays on both visits, one for $2500 (4 Kings $10 DDB) and $12,000 (4 As $10 TBP)...when I hit the 4 Kings the machine asked if I wanted to double up...when I hit the Aces it just locked up without an option to double up...any idea what IGT sets the limit at for double ups? Or does it depend on the year and make of the machine? Just wondering, thanks...

[Tedlark]

The casino may have requested the limit when ordering the machine from IGT.

[Vman96]

I have read the max double up is 20k credits by default, but it could also be set lower.