While I can see some surface comparisons, I don't think one is necessarily a 'version' of the other.
Kindred's shredding powers are highly localized to a limited region. You can simply elect to team fight else where when she drops Wolf's Frenzy, then reengage once it's down. Or simply knock her out of the region with displacement. Kog'maw on the other hand brings his shred with him everywhere he goes and, in certain builds, can have it up practically 'on demand' late game. Making Kindred more about zone-control and Kog'maw more about mobile-artillery.
The same applies to their style of executions. Kindred's Mounting Dred can only focus on one low individual at a time, highlighting her lane-oriented emphasis. Where as Kog'Maw will always be getting his bonus damage per low health increase no matter if he's hit the target prior or not.
So overall while Kindred and Kog'maw are both marksman, the former is more designed to lean towards assassination as a secondary while the other one if more of a caster.
Different enough that I don't think the strength of one should call for improvements in the other by virtue of that alone. ^_^