diff --git a/src/aioweb/preview.py b/src/aioweb/preview.py
index 3435e54..e50db7c 100644
--- a/src/aioweb/preview.py
+++ b/src/aioweb/preview.py
@@ -36,8 +36,9 @@ class RequestPreview:
         if self.details["data"] is not None:
             data = self.details["data"]
             # aiohttp form-encodes a dict data= body (application/x-www-form-urlencoded);
-            # render that wire form, not the python repr, so the curl replays identically
-            rendered = urlencode(data) if isinstance(data, dict) else str(data)
+            # render that wire form, not the python repr, so the curl replays identically.
+            # doseq=True mirrors aiohttp's FormData: a list value becomes repeated k=v pairs
+            rendered = urlencode(data, doseq=True) if isinstance(data, dict) else str(data)
             parts.append(f"--data {shlex.quote(rendered)}")
         elif self.details["json"] is not None:
             # is-not-None: an empty-but-valid body ({} / []) must still render