diff --git a/src/score/alphatex.ts b/src/score/alphatex.ts
index 5cb566a..2de2b93 100644
--- a/src/score/alphatex.ts
+++ b/src/score/alphatex.ts
@@ -25,11 +25,15 @@ function checkGrid(v: number, what: string): void {
 /** Group by onset; length = shortest dur in group clipped to next onset; gaps become rests; padded to totalTicks. */
 function buildBeats(notes: ScoreNote[], totalTicks: number): Beat[] {
   const groups = new Map<number, ScoreNote[]>();
+  const seen = new Set<string>();
   for (const n of notes) {
+    const key = `${n.tick}:${n.pitch}`;
+    if (seen.has(key)) continue; // exact duplicate (same tick+pitch)
+    seen.add(key);
     checkGrid(n.tick, "tick");
     checkGrid(n.dur, "dur");
     if (n.dur <= 0) throw new Error("note dur must be > 0");
-    if (n.tick + 0 >= totalTicks) throw new Error(`note at tick ${n.tick} beyond song end ${totalTicks}`);
+    if (n.tick >= totalTicks) throw new Error(`note at tick ${n.tick} beyond song end ${totalTicks}`);
     (groups.get(n.tick) ?? groups.set(n.tick, []).get(n.tick)!).push(n);
   }
   const ticks = [...groups.keys()].sort((a, b) => a - b);
@@ -92,7 +96,7 @@ function trackToTex(track: Track, barTicks: number, bars: number): string {
       const segEnd = Math.min(end, barEnd);
       for (const piece of decompose(segEnd - pos)) {
         const tie = !first && !drums && beat.notes.length > 0;
-        const body = beat.notes.length === 0
+        const body = beat.notes.length === 0 || (drums && !first)
           ? "r"
           : beat.notes.length === 1 ? noteText(track, beat.notes[0]!, tie) : `(${beat.notes.map((n) => noteText(track, n, tie)).join(" ")})`;
         perBar[Math.floor(pos / barTicks)]!.push(`:${piece.div} ${body}${piece.dotted ? " {d}" : ""}`);
diff --git a/src/score/gp.ts b/src/score/gp.ts
index 3691877..1fd73b1 100644
--- a/src/score/gp.ts
+++ b/src/score/gp.ts
@@ -41,6 +41,8 @@ export function songToMidi(song: Song): at.midi.MidiFile {
   return midi;
 }
 
+const ROLES: readonly string[] = ["guitar", "bass", "keys", "vocals", "drums"];
+
 export function truthFromGp(bytes: Uint8Array): { bpm: number; timeSig: [number, number]; tracks: TruthTrack[] } {
   const score = at.importer.ScoreLoader.loadScoreFromBytes(bytes, new at.Settings());
   const bpm = score.tempo;
@@ -73,6 +75,7 @@ export function truthFromGp(bytes: Uint8Array): { bpm: number; timeSig: [number,
         }
       }
     });
+    if (!ROLES.includes(track.shortName as Role)) throw new Error(`track "${track.name}": shortName "${track.shortName}" is not a valid Role`);
     const tr: TruthTrack = { name: track.name, role: track.shortName as Role, notes };
     if (!track.isPercussion) tr.tuning = [...staff.tuning];
     return tr;
diff --git a/tests/score/roundtrip.test.ts b/tests/score/roundtrip.test.ts
index c2f28ff..871b86a 100644
--- a/tests/score/roundtrip.test.ts
+++ b/tests/score/roundtrip.test.ts
@@ -80,3 +80,34 @@ test("GP round trip preserves notes, ties, strings, roles", () => {
 test("songToMidi generates events", () => {
   expect(songToMidi(song).tracks.length).toBeGreaterThan(0);
 });
+
+function drumSong(notes: { tick: number; dur: number; pitch: number }[]): Song {
+  return {
+    title: "d", tier: "t1", seed: 1, bpm: BPM, timeSig: [4, 4], bars: 2, key: "C",
+    tracks: [{ name: "Kit", role: "drums", program: 0, pan: 0, fx: "none", gainDb: 0, notes }],
+  };
+}
+
+test("drum note with multi-piece duration yields exactly one hit", () => {
+  const truth = truthFromGp(songToGp(drumSong([{ tick: 0, dur: 5 * S, pitch: 38 }])));
+  expect(truth.tracks[0]!.notes.map((n) => [n.pitch, n.onset])).toEqual([[38, 0]]);
+});
+
+test("drum note crossing a barline yields exactly one hit", () => {
+  const truth = truthFromGp(songToGp(drumSong([{ tick: 3 * Q, dur: 2 * Q, pitch: 36 }])));
+  expect(truth.tracks[0]!.notes.map((n) => [n.pitch, round3(n.onset)])).toEqual([[36, round3(t(3 * Q))]]);
+});
+
+test("exact duplicate notes are de-duplicated", () => {
+  const dup = { tick: Q, dur: Q, pitch: 60 };
+  const s = drumSong([]);
+  s.tracks = [{ name: "V", role: "vocals", program: 53, pan: 0, fx: "none", gainDb: 0, notes: [dup, { ...dup }] }];
+  const truth = truthFromGp(songToGp(s));
+  expect(truth.tracks[0]!.notes.length).toBe(1);
+});
+
+test("truthFromGp rejects an invalid role short name", () => {
+  const s = drumSong([{ tick: 0, dur: Q, pitch: 36 }]);
+  (s.tracks[0] as any).role = "banjo";
+  expect(() => truthFromGp(songToGp(s))).toThrow(/not a valid Role/);
+});