This is a common occurrence in Pali sandhi (combining words).
For example, Dhammacakka Pavattana are combined to yield Dhammacakkappavattana.
– Pancakkhandha is the combination of panca with khandha with an additional k in tying up the two words.
P.S. Sometimes a letter is removed in the process of combining words.
– For example, in Dhammacakkappavattana Sutta there is a key verse: “yampicaam nalabhati tampi dukkham“.
– Here “yam pi iccam” combimed to yield “yampiccam” and an “i” was dropped.
It is easier to pronounce that way.