diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -842,9 +842,16 @@ class dirstate(object):
                 audit_path = pathutil.pathauditor(self._root)
 
                 for nf in iter(visit):
+                    # If a stat for the same file was already added with a
+                    # different case, don't add one for this, since that would
+                    # make it appear as if the file exists under both names
+                    # on disk.
+                    if (normalizefile and
+                        normalizefile(nf, True, True) in results):
+                        results[nf] = None
                     # Report ignored items in the dmap as long as they are not
                     # under a symlink directory.
-                    if audit_path.check(nf):
+                    elif audit_path.check(nf):
                         try:
                             results[nf] = lstat(join(nf))
                             # file was just ignored, no links, and exists
diff --git a/tests/test-casefolding.t b/tests/test-casefolding.t
--- a/tests/test-casefolding.t
+++ b/tests/test-casefolding.t
@@ -37,6 +37,15 @@ Case-changing renames should work:
   $ hg mv A a
   $ hg st
 
+addremove after case-changing rename has no effect (issue4590)
+
+  $ hg mv a A
+  $ hg addremove
+  recording removal of a as rename to A (100% similar)
+  $ hg revert --all
+  forgetting A
+  undeleting a
+
 test changing case of path components
 
   $ mkdir D