In 1982, LEGO released 1 Duplo Supplementary sets, all of these sets have been retired.
1 set

2306-2 Supplementary Bricks

Theme / Subtheme Duplo / Supplementary
Year 1982
Pieces 18
Availability Retired
2306-2 LEGO Duplo Supplementary Bricks
Retail $9.99
Value $30.40
Growth  +204.3%
Annual growth 2.6%