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+Attempt was made to import an item whereas an extern crate with this name has
+already been imported.
+
+Erroneous code example:
+
+```compile_fail,E0254
+extern crate core;
+
+mod foo {
+    pub trait core {
+        fn do_something();
+    }
+}
+
+use foo::core;  // error: an extern crate named `core` has already
+                //        been imported in this module
+
+fn main() {}
+```
+
+To fix this issue, you have to rename at least one of the two imports.
+Example:
+
+```
+extern crate core as libcore; // ok!
+
+mod foo {
+    pub trait core {
+        fn do_something();
+    }
+}
+
+use foo::core;
+
+fn main() {}
+```