Steps to reproduce:
1. Open a JFR file, and go to the Thread Dumps page.
2. Expand a thread dump node.
3. Select two leaves in the tree, context click and select "Copy" (or press CTRL+C).
4. Paste the text in an editor.

==> You will have the thread dump header copied twice.

Here's an example:

---------------------
{{
2013-05-30 13:48:25
Full thread dump Java HotSpot(TM) Client VM (24.0-b45 mixed mode):

JNI global references: 945

"Java2D Disposer" daemon prio=10 tid=0x1803b400 nid=0x1bf0 in Object.wait() [0x00c5f000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)

• waiting on <0x0924e9a0> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
• locked <0x0924e9a0> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
  at sun.java2d.Disposer.run(Disposer.java:145)
  at java.lang.Thread.run(Thread.java:722)

2013-05-30 13:48:25
Full thread dump Java HotSpot(TM) Client VM (24.0-b45 mixed mode):

JNI global references: 945

"Finalizer" daemon prio=8 tid=0x00a28800 nid=0x1d04 in Object.wait() [0x00daf000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)

• waiting on <0x0924ecb8> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135)
• locked <0x0924ecb8> (a java.lang.ref.ReferenceQueue$Lock)
  at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:151)
  at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:189)}}

The header part is this:

{{2013-05-30 13:48:25
Full thread dump Java HotSpot(TM) Client VM (24.0-b45 mixed mode):

JNI global references: 945}}