Seems so, yes...

Sources I've looked at (Google tropical wood density) give specific gravities for the two as .37 for okoume wood (Acoumea klaineana) and .43 for plywood (27 lbs / cu ft), while for sapele (Entandrophragma cylindricum) the wood's SG might range from .45 to .67 (one source gives 42 lbs / cu ft).

I haven't found a density number listed for sapele plywood.

Looking elsewhere here at CLC'S descriptions of these two plywoods they can provide puts okoume 4mm @ 13#/sheet, sapele @ 18#/sheet, the latter being ~ 40% heavier.

So 150 - 200% seems a reasonable expectation... unless you can arrange for an opportunity to pick & choose the sheet(s) you're purchasing by weight.

Spclark nailed the numbers.

My question is where do you plan to use the Sapelle?  You could use 3mm Sapelle in many places that you would use 4mm Okoume, and the two weigh virtually the same.  A 4'x8' sheel of 3mm Sapelle weighs 14# where a sheet of 4mm Okoume weighs 13#.  I would not make that substitution on the hull of a kayak but would certainly consider it for a deck.  Personally, I love the look of Sapelle and use it (3mm) for the cockpit coaming and bulkheads in my strip boats.  The one warning about Sapelle is that it does not bend as well as Okoume.