Macro are not accumulated and yet they are

[MysaaJava]

Take the following two files:
a.elpi

macro @mcro X :- X = 12.

b.elpi

accumulate "a".

pred test o:int.
test X :- @mcro X.

Running test predicate on file b gives error:
Unknown macro @mcro. Known macros:

If we add macro @mcro X :- X = 12. to b.elpi, this works again.

But if we add a different macro with the same name, like for example macro @mcro X :- X = 13., it will fail with

Macro @mcro declared twice.
File "./a.elpi", line 1, column 0, characters 0-23: 
  X: int \ X = 12
File "./b.elpi", line 3, column 0, characters 17-40: 
  X: int \ X = 13

So the data of the macro seems to be available to the typechecker somewhere.