Steve,
Your rencong is quite uncommon.
Most scabbards are from 1 solid piece of wood, indeed hollowed from the back side which is than covered with a strip of wood again.
In some cases so tight that I wondered if there was a strip.
Than I have now one rencong with a scabbard made out of one piece, and also 1 with a scabbard made out of 2 separates sides (left and right)
Buffalo horn scabbards are rare, but IMO more recent and/or made for 'tourist' rencongs.
I have seen a few Hulu dandan rencongs with scabbard mouths made of ivory.
So far my observations.
Although I love these weapons I don't have much documentation on them accept for a free download that came from
www.mytribalworld.com
Best regards,
Willem