It looks like the same guy from Sayid's flashback. While Des and Kelvin were talking, Kelvin said to Des somthing along the lines of "What army were you in again? Oh ya the queens army. You took orders from a woman?" Then Des said "And what hapened to your army?" Then Kelvin looked away, hurt. Kelvin also said that he joined Dharma after he left the army. A very likely connection.

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"See you in another life, brother." -Desmond