Add ui test of duplicate generics in remote derive

test_suite/tests/ui/remote/double_generic.rs

@@ -0,0 +1,17 @@
+use serde_derive::{Deserialize, Serialize};
+
+mod remote {
+    pub struct Struct<T, U> {
+        pub t: T,
+        pub u: U,
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+#[serde(remote = "remote::StructGeneric<u8>")]
+struct StructDef<U> {
+    t: u8,
+    u: U,
+}
+
+fn main() {}