Donruss has included a Diamond King subset in almost each one of their sets. It debuted in 1982, their second year and has been a stable for each set with the exception of 1997 and 1998. It seemed that early on, at least for the Cubs, a different player was selected each year. The first Cub repeat king was Ryne Sandberg. He was the king in 1985 and again in 1991. Ryno was named a third time in 1993 and at that point, it doesn't seem like Donruss tried to spread the wealth.
Mark Grace was a repeat, with both 1989 and 1996. Sammy Sosa was named king five times, in 1995, 2001 - 2003, and 2005. The modern sets saw Anthony Rizzo getting names five times also, in 2014, 2015, 2017, 2018, and 2021.
Below is the complete court of Cubs Diamond Kings.