Explanation for extended phase 10 5 sets of 2 in the same color
May not have been the original intent, but far more doable: "5 sets of 2, with one color shared between all the sets."

IE

R2G2
R3B3
R5G5
R7Y7
R9G9

would be a valid hand, since you have 5 sets of two and each set has a red card in it.



If it's the same set of rules as was linked above, #19 there is "19. 5 sets of 2 in same color - wild card color must match number color". The context on the site makes it clear they intended all 10 of the cards to be the same color. It does seem to be a bit restrictive, but note that the wild cards can smooth out the missing duplicate numbers. 

Also, "Note: The above rules use Phase 10 cards with colored wild cards. In some newer decks all the wild cards are the same color. If playing with this type of deck, just disregard the restrictions on wild card colors."