What is the largest daily double ever on jeopardy?

For season 26 it is $13,800 and a True Daily Double (TDD) on 1 21 10

For season 25 it was $10,800 and a TDD on both 12 1 08 and 12 3 08

For season 24 it is $12,000 on 7 21 08

For season 23 it is $10,000 on 2 8 07

For season 22 it is $10,000 on 11 3 05

For season 21 was 13,200 and 12,000 for Ken Jennings on 11 24 04 and 10 6 04

These answers come from the related link Daily double statistics at the bottom row for each season.