3Ware 9650SE is rebuilding RAID6 array with two degraded disks?

I have a RAID6 array on a 3Ware 9650SE which is degraded:

 tw_cli /c0/u0 show

Unit     UnitType  Status         %RCmpl  %V/I/M  Port  Stripe  Size(GB)
------------------------------------------------------------------------
u0       RAID-6    REBUILDING     60%(A)  -       -     256K    5587.9    
u0-0     DISK      DEGRADED       -       -       p0    -       1862.63   
u0-1     DISK      OK             -       -       p1    -       1862.63   
u0-2     DISK      OK             -       -       p2    -       1862.63   
u0-3     DISK      OK             -       -       p3    -       1862.63   
u0-4     DISK      DEGRADED       -       -       p4    -       1862.63   
u0/v0    Volume    -              -       -       -     -       50        
u0/v1    Volume    -              -       -       -     -       5537.9

Two disks are degraded, which is the maximum for RAID6, so how can it be rebuilding?

Edit:

I noticed that the lights of the degraded disks were still blinking and the error led wasn't turned on, so they hadn't really been marked as failed.

The Rebuild is done, and now this is the output:

Unit     UnitType  Status         %RCmpl  %V/I/M  Port  Stripe  Size(GB)
------------------------------------------------------------------------
u0       RAID-6    INITIALIZING   -       35%(A)  -     256K    5587.9
u0-0     DISK      OK             -       -       p0    -       1862.63
u0-1     DISK      OK             -       -       p1    -       1862.63
u0-2     DISK      OK             -       -       p2    -       1862.63
u0-3     DISK      OK             -       -       p3    -       1862.63
u0-4     DISK      OK             -       -       p4    -       1862.63
u0/v0    Volume    -              -       -       -     -       50
u0/v1    Volume    -              -       -       -     -       5537.9

So apparently, a 'DEGRADED' disk can still be part of a rebuild. Am I right in assuming this should have been a state like 'DEGRADED_BUT_PART_OF_REBUILD' or 'PREVIOUSLY_DEGRADED'?

I think it's just bad terminology. In a strict sense, individual disks cannot be "degraded", so the state should have been displayed as "OK, REBUILDING" (and this is how the term "DEGRADED" should be interpreted with 3Ware controllers when applied to a disk).

That was a normal partial rebuild operation in a RAID6. Note that the 9650SE has a particularly nasty bug that will mark one disk in a RAID6 as requiring a rebuild when the system isn't shut down properly.