This is pretty bad when you can't get something back with it, but you can get that 2-for-1 often enough for it to be pretty good overall
Jumpstart: Historic Horizons Spellbook Cards Tome of the Infinite Spellbook Swords to Plowshares Force Spike Lightning Bolt Fog Light of Hope Dark Ritual Assault Strobe Ponder Duress Giant Growth One of the few entries without a full 15 cards, but these are pretty bonkers
Second, we lose the Ghost Quarters and Tectonic Edge from our mana base
Tundra: Plains Island Underground Sea: Island Swamp Badlands: Swamp Mountain Taiga: Mountain Forest Savannah: Forest Plains Scrubland: Plains Swamp Bayou: Swamp Forest Tropical Island: Forest Island Volcanic Island: Island Mountain Plateau: Mountain Plains The main value of a Dual Land Set is mana consistency
Unlike the retro-framed reprints, these are not guaranteed to be found in every pack
Mrmoustachemm and Cold-cryptic suggested Companions that limited your land picks, but as Rosewater pointed out, that doesnt really lead to interesting deck building