What is the information source that the Conn violin finished clarinets are cocobolo? 
I am forever skeptical;- please forgive me.
And well you should be. As much as there's a problem with "tung oil", there's a real problem with wood species identification. The trade name "cocobolo" itself is given to wood from multiple species of (closely-related) tree. (Think "oak". Consider the difference between red oak and white oak.)
What's interesting is that while official sources (e.g. WP) state that it's rare outside of parks, reserves, and plantations, my father said it was everywhere when he visited Costa Rica back in the nineties. (I do see that the CITES listing was as of the late aughties.)
My wood-working instructor was always on the look-out for pallets from South America as he had found that they were often made of the stuff. He told a tale of a fellow who imported straw hats that were crated in cocobolo on cocobolo pallets.
Visual identification only gets us so far, but given an assembled instrument, it's mostly what we can go by. Given the '50 to '54 advertising, I think that it's safe to assume that they were working with post-War stocks of materials. Woodwinds didn't appear in Conn's '48 "Temporary Price list" but they did re-appear in '49:
http://www.saxophone.org/museum/publications/id/493 (clarinets appear on page 6; click to embiggen any one page image) The grenadilla was obviously reserved for Conn's more expensive instruments but not in sufficient quantities (how much ended up in the clutches of the Third Reich?) to supply Conn for their Pan-American line, hence the substitution.
Grenadilla and Cocobolo are both
Dalbergia, so trying a substitution is obvious. You want something that hopefully starts out dimensionally-stable and stays that way, to reduce waste and cracking, respectively.
Similar physical properties with respect to shrinkage:
http://www.wood-database.com/african-blackwood/ http://www.wood-database.com/cocobolo/Cocobolo isn't quite as hard or dense as Grenadilla, but is otherwise quite similar.
Given the examples I've seen, there may very well be some laminated clarinets out there, but I would go with "rapid growth wood" for the ones with the wide striping.