On the first disc:

I 11:03:20 Operation Started!
I 11:03:20 Device: [0:1:0] MATSHITA BD-CMB UJ141AS 1.00 (E:) (ATAPI)
I 11:03:20 Media Type: DVD-RW (Disc ID: RITEKF1)
I 11:03:20 Media Supported Write Speeds: 2x, 3.3x, 4x, 6x, 8x
I 11:03:20 Quick Erase: No
I 11:03:24 Erasing Disc...
E 11:03:27 Failed to Erase Disc! - Reason: Cannot Write Medium - Incompatible Format
E 11:03:27 Operation Failed! - Duration: 00:00:07

----------------------------------------------------------------------------------------------------
On the other disc:


I 11:06:32 Operation Started!
I 11:06:32 Device: [0:1:0] MATSHITA BD-CMB UJ141AS 1.00 (E:) (ATAPI)
I 11:06:32 Media Type: DVD-RW (Disc ID: TYG02)
I 11:06:32 Media Supported Write Speeds: 2x, 3.3x, 4x, 6x, 8x
I 11:06:32 Quick Erase: No
I 11:06:32 Erasing Disc...
E 11:06:36 Failed to Erase Disc! - Reason: Cannot Write Medium - Incompatible Format
E 11:06:36 Operation Failed! - Duration: 00:00:03