Is it a keris and from which island?

[Sajen]

Dear members,

I have the option to buy this keris (?) and have the allowance to post the pictures here. Since it have a seperate gonjo even if it hasn't the overall look like a keris I post it here. The handle is from hippo ivory and the ferrule is from horn. I have never seen something like this and want to ask you if you have. The sheat looks sumatran so I think it's from there or maybe from Borneo.

All comments are very appreciated and welcome,

Detlef