Checks for branches in if blocks with equivalent conditions.
This is most likely a copy and paste error.
if foo then print(1) elseif foo then print(1) end
This ignores conditions that could have side effects, such as function calls. This will not lint:
if foo() then print(1) elseif foo() then print(1) end
...as the result of
foo() could be different the second time it is called.