Absolutely.
When running SAS will return the result from the "inner most" scope. Think of macro scope like nesting dolls.
If the macro variable MVAR1 exist as GLOBAL (or some outer scope) but your macro (or some intervening macro scope) also has a local macro variable named MVAR1 then that outer version is hidden.
If you really need know what the value in that outer scope is you could use this utility macro.
https://github.com/sasutils/macros/blob/master/symget.sas
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