skos:closeMatch and skos:exactMatch

I have (hopefully) one final question about SKOS. My understanding is that
all the sub-properties of skos:mappingRelation are meant to map between two
different ConceptSchemes. In the SKOS Reference
<https://www.w3.org/TR/skos-reference/#mapping> it says:

The SKOS mapping properties are skos:closeMatch, skos:exactMatch,
> skos:broadMatch, skos:narrowMatch and skos:relatedMatch. These properties
> are used to state mapping (alignment) links between *SKOS concepts in
> different concept schemes*, where the links are inherent in the meaning
> of the linked concepts.


My question is about skos:closeMatch and skos:exactMatch. For all the other
mapping properties there are equivalent properties that aren't
sub-properties of skos:mappingRelation. So if  Animal and Mammal are in the
same Concept Scheme and I want to assert that ex1:Animal skos:narrower
ex1:Mammal I can do that and if they were in different Concept Schemes I
would say ex1:Animal skos:narrowerMatch ex2:Mammal.

If I have two synonym Concepts in two different ConceptSchemes:
ex1:TheMorningStar and ex2:TheEveneningStar I can say
ex1:TheMorningStar skos:exactMatch ex2:TheEveningStar. But what if they are
in the *same *Concept Scheme? If I want to say ex1:TheMorningStar is
identical to ex1:TheEveningStar there doesn't seem to be a way to do that.
Similarly if I want to say they are close but not quite exact synonyms
(e.g., ex1:Customer and ex1:Client) What am I missing?

Cheers,
Michael
https://www.michaeldebellis.com/blog