The layerbreak hasn't anything to do with it...
It's simply that a burned media is harder to read for a laser.
Why? Because normally pressed discs don't have C1/C2 PI/PO-Errors, or atleast at a really low rate (and normally those are badly mastered).
Now on a burned DL-Disc it has to focus onto a second burned layer and correct all those read-errors, while 'looking through a blurry window' a.k.a. the first half-transparent layer.
I agree to l_oliveira here.
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
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PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
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