They also appeared in a segment of a 1993 Japanese TV show, apparently called Naruhodo The World.
*OK, I know some readers are gonna say, "Videocassettes?! Oh yeah... I heard o' those... How old are you again?"
**not the contemporary performers: they're 'one-R' Foresters...
These are from the days when American anime fandom was becoming large enough to need to break away from their niche in science-fiction conventions and have their own gatherings (many of which are now easily as big as the biggest SF cons). Translated video was still pretty hard to come by then, but DP could cross the metaphorical bridge across the Pacific, since the series wasn't heavy on dialog, had lots of action, and few storylines where details of plot hinged on subtleties of language.
That ease of transoceanic transition made it one of the series that American fans, starting in 1986, could pick up on easily.† Many of those fans went on to found companies that brought over and translated more anime -- a process that soon underwent runaway growth. It also led to DP continuing to be a perennial in anime catalogs for 25 years†† (thus far, as witness the blog entry below for 2 July...).
†Soon afterwards in Europe, DP was dubbed for French television (as Dan et Danny) in 1989 and into Italian (as Kate e Julie) in '92.
††if you start counting from listing of fans "duping" VHS tapes... (yeah okay, I am old -- you gotta problem wi'that?)
Here's some pix -- the Forresters above, Beth and Honey-chan below them: