Duplicating sprite should give new sprite a fresh name.

src/sprites/sprite.js

@@ -84,7 +84,7 @@ class Sprite {
 
         newSprite.blocks = this.blocks.duplicate();
 
-        const allNames = this.runtime.targets.map(t => t.name);
+        const allNames = this.runtime.targets.map(t => t.sprite.name);
         newSprite.name = StringUtil.unusedName(this.name, allNames);
 
         const assetPromises = [];

test/unit/virtual-machine.js

@@ -276,6 +276,26 @@ test('duplicateSprite duplicates a sprite when given id is associated with known
 
 });
 
+test('duplicateSprite assigns duplicated sprite a fresh name', t => {
+    const vm = new VirtualMachine();
+    const spr = new Sprite(null, vm.runtime);
+    spr.name = 'sprite1';
+    const currTarget = spr.createClone();
+    vm.editingTarget = currTarget;
+
+    vm.emitWorkspaceUpdate = () => null;
+
+    vm.runtime.targets = [currTarget];
+    t.equal(vm.runtime.targets.length, 1);
+    vm.duplicateSprite(currTarget.id).then(() => {
+        t.equal(vm.runtime.targets.length, 2);
+        t.equal(vm.runtime.targets[0].sprite.name, 'sprite1');
+        t.equal(vm.runtime.targets[1].sprite.name, 'sprite2');
+        t.end();
+    });
+
+});
+
 test('emitWorkspaceUpdate', t => {
     const vm = new VirtualMachine();
     vm.runtime.targets = [