This is true.
If you need to re-stamp a decal onto the same place on a model but perhaps the mesh has been edited since or you want to include neighboring patches, you can continue down to the "Stamp" folder underneath the decal, on the Stamp for the decal and choose "Recall View/Position". This perches the decal in the correct position ready for you to "apply" again. Then you would delete the original stamp in the stamp folder.
Before you do this, you need to have the window open that you originally applied the decal in. Typically that's a model window, but it is also possible to apply decals in Pose WIndows. You would need to have that Pose window open and set to whatever ON/OFF or Percentage setting you used for the decal.
If you had some of the mesh hidden when you first applied the decal you will want to re hide it.