diff --git a/spec_registry.go b/spec_registry.go
index 610806e..8ce659d 100644
--- a/spec_registry.go
+++ b/spec_registry.go
@@ -23,6 +23,9 @@ func RegisterSpecGroups(groups ...RouteGroup) {
 		if group == nil {
 			continue
 		}
+		if specRegistryContains(group) {
+			continue
+		}
 		specRegistry.groups = append(specRegistry.groups, group)
 	}
 }
@@ -37,3 +40,30 @@ func RegisteredSpecGroups() []RouteGroup {
 	copy(out, specRegistry.groups)
 	return out
 }
+
+// ResetSpecGroups clears the package-level spec registry.
+// It is primarily intended for tests that need to isolate global state.
+func ResetSpecGroups() {
+	specRegistry.mu.Lock()
+	defer specRegistry.mu.Unlock()
+
+	specRegistry.groups = nil
+}
+
+func specRegistryContains(group RouteGroup) bool {
+	key := specGroupKey(group)
+	for _, existing := range specRegistry.groups {
+		if specGroupKey(existing) == key {
+			return true
+		}
+	}
+	return false
+}
+
+func specGroupKey(group RouteGroup) string {
+	if group == nil {
+		return ""
+	}
+
+	return group.Name() + "\x00" + group.BasePath()
+}
diff --git a/spec_registry_test.go b/spec_registry_test.go
new file mode 100644
index 0000000..dbd20f0
--- /dev/null
+++ b/spec_registry_test.go
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: EUPL-1.2
+
+package api_test
+
+import (
+	"testing"
+
+	"github.com/gin-gonic/gin"
+
+	api "dappco.re/go/core/api"
+)
+
+type specRegistryStubGroup struct {
+	name     string
+	basePath string
+}
+
+func (g *specRegistryStubGroup) Name() string                       { return g.name }
+func (g *specRegistryStubGroup) BasePath() string                   { return g.basePath }
+func (g *specRegistryStubGroup) RegisterRoutes(rg *gin.RouterGroup) {}
+
+func TestRegisterSpecGroups_Good_DeduplicatesByIdentity(t *testing.T) {
+	snapshot := api.RegisteredSpecGroups()
+	api.ResetSpecGroups()
+	t.Cleanup(func() {
+		api.ResetSpecGroups()
+		api.RegisterSpecGroups(snapshot...)
+	})
+
+	first := &specRegistryStubGroup{name: "alpha", basePath: "/alpha"}
+	second := &specRegistryStubGroup{name: "alpha", basePath: "/alpha"}
+	third := &specRegistryStubGroup{name: "beta", basePath: "/beta"}
+
+	api.RegisterSpecGroups(nil, first, second, third, first)
+
+	groups := api.RegisteredSpecGroups()
+	if len(groups) != 2 {
+		t.Fatalf("expected 2 unique groups, got %d", len(groups))
+	}
+
+	if groups[0].Name() != "alpha" || groups[0].BasePath() != "/alpha" {
+		t.Fatalf("expected first group to be alpha at /alpha, got %s at %s", groups[0].Name(), groups[0].BasePath())
+	}
+	if groups[1].Name() != "beta" || groups[1].BasePath() != "/beta" {
+		t.Fatalf("expected second group to be beta at /beta, got %s at %s", groups[1].Name(), groups[1].BasePath())
+	}
+}