[RickOShay]

Umm it is just how the counter works.. it is still saying ichi いち, but when said with ki the pronunciation changes from ichi, to i いっ, this is a small tsu っ, used to indicate a brief pause between the i, and the ki. and it is written in romaji by using a double consonant.. in this case "kk"

Counters in Japanese are frigging endless, there is even a drinking game Japanese people play using the billion different counters they have.