cache entries clash for 2 spaces with page and MultiExcerpt name that match
in Space 1 create a page "FooPage" with a MultiExcerpt "FooME", publish.
include the excerpt in another page in Space 1 using MultiExcerpt Include, publish.
in Space 2 do the same, matching the "FooPage" and "FooME" names.
when you make a change to the content of the excerpt in Space 1 and publish it will update the cache.
then view the ME-Include in Space 2 and notice it sees the cached content from the Space 1 excerpt.
Create a Support Ticket
fixed in 5.4.3