These kinds of details changed several times with "Dynasty" ...
Yes. Like Jason, in S6, having the exclusive right from the Chinese govt to ship out all oil pumped in the South China Sea; which was why he could tell Blake that Blake could ship his oil out on a rubber dinghy for all he cared if Blake didn't agree to partner him in building the oil pipeline. Then, it's changed: lo and behold, in the latter half of S6, here's Zach trying to cut a deal with Blake to bring the oil into port as if Blake had a choice of shippers... and as if Zack wasn't already Jason's partner (to whom he should have been speaking about how Jason could get around the American harbour ban, not Blake) & as if Jason didn't have any other alternative way to 'land' the oil. IMO, Dynasty should have,
could have, made that meeting between Zach and Blake about something else* & without that total hostility on Blake's part (in that first appearance) since that was already shown to be lacking on TC. But there it was, totally out of the blue.
*Zack on TC was interested in established businesses that were doing well. No sign of his interest in start-ups. In preparation for RM's 2nd appearance in early S7, Dynasty could have used his 1st appearance to lay the groundwork: Zach's in town at Alexis's behest, and he pays Blake a courtesy call. (After all, Zack's already shipping some of Blake's S.C.S oil.) Mentions he's thinking of branching out of the shipping industry, is considering various directions, blah, blah..., maybe even fund new ventures, and sounds out Blake for advice. That could explain his business interest in his 2nd appearance ....but not his abject failure in knowing how to negotiate profitable terms, the dunce.
Also, on TC, the backstory is police thought Zack's wife's death at sea was an accident. Which doesn't square with Caress's backstory on Dynasty.
It seems either Dynasty used as many ways as possible to ensure viewers could tell the difference between Zack & Zach; or else Dynasty just couldn't care less about reconciling details: RM was making only 2 guest appearances, so why bother. (Instead of, why not make the effort. Unless, again, Zack & Zach weren't meant to be playing the same character arc.) Regardless, when it came to writing for its guest stars, TC treated its guest stars more respectfully.