Top: the second of two identical GPUs draws its busy graph

Its sensors were gpu.<name>.usage_2 and so on; the page looks under gpu.<name>_2. Each
card now gets its own stem, as the page already assumed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/metrics/sensors.go

@@ -142,8 +142,14 @@ func flatten(s Sample, want func(id string) bool) []sensors.Sensor {
 		f.add(p+".used_pct", x.Mount+" used", "usage", "%", ratio(x.Used, x.Size), s.fsT, pct, lbl...)
 	}
 
+	gpuSeen := map[string]int{}
 	for _, g := range s.GPUs {
+		// two identical cards are gpu.<name> and gpu.<name>_2, every sensor of the second under
+		// its own stem (not add's suffix on the end of each id, which the page can't find)
 		p := "gpu." + sensors.Seg(g.Name)
+		if gpuSeen[p]++; gpuSeen[p] > 1 {
+			p = fmt.Sprintf("%s_%d", p, gpuSeen[p])
+		}
 		lbl := []string{"name", g.Name, "driver", g.Driver}
 		if g.Bus != "" {
 			lbl = append(lbl, "bus", g.Bus)