Uniqueness and overloading

[ecceso@eucmos.sim.ucm.es]

I have been playing with clean arrays, and I am astonished because of
an error message. I wanted to copy an array, so I wrote

  copy as = {a \\ a<-:as} 

The clean compiler accepts this definition and types it as

  copy :: (a b) -> *(c b) | Array a & Array c & createArray_u, 
defaultArrayvalue, update_u, uselect_u, usize_u b

Then, I tried a function to copy an array with two levels
  
  copy2Levels ass = {copy as \\ as<-:ass} 
  
But I got this error:

  Conflicting uniqueness information due to argument2 of createArray

I don't understand why there is a problem with uniqueness. The function
copy returns an unique array. Even more, if I define a restricted version
of copy

  copy2 :: (a b) -> *{b} | Array a & createArray_u, defaultArrayvalue, update_u, 
uselect_u, usize_u b //This is a restriction of the type inferred by clm.
  copy2 as = {a \\ a<-:as}
  
which returns a fixed class of array, then I can define copy2Levels without
problems

  copy2Levels2 ass = {copy2 as \\ as<-:ass}

The type inferred by clm is

  copy2Levels2 :: (a (d b)) -> *(c {b}) | Array a & Array c & Array d & 
createArray_u, defaultArrayvalue, update_u, uselect_u, usize_u b

I don't understand why overloading interferes with uniqueness.
Are there interactions? Can anyone explain me this? 
Or is this only a bug in the type inference algorithm?

Thanks,
  Pedro.