DSi Originally Had Two DS Slots

Check out this nice article. It basically explains that the DSi was orginally going to have 2 DS game slots.

The DSi will be arriving in the States pretty soon, and alas, it will be lack a
GBA port. But according to a new Iwata Asks interview, the DSi wasn't always a
one port system. While still in the design stages, the DSi had two slots for
DS games, said Nintendo development engineer Masato Kuwahara. The change was
implemented in response to fan requests, but as it turned out, it made the DSi a
great deal bulkier. In the end, they had to drop it.

"The response wasn't that great, and, to tell the truth, we'd sort of been expecting that," said Kuwahara. "According to the determined specifications, however, there was nothing we could do to stop it from turning out like that. We unveiled it to
them, all the while doubting that it was going to be all right."

Kuwahara also said that the relatively marginal changes between the DS
Lite and the DSi were a "source of frustration" for him, but that he hoped that
features like the larger LCD screens and new matte finish would make the fans
happy.

[via gametab.com]