DVD rescue: Rescued data in mapfile goes past end of input file ?

[Fab Stz]

Hello,

I started to run ddrescue on a personal DVD (device /dev/cdrom) on a amd64 
system running ddrescue 1.27.

To check with another CD/DVD reader on another PC I wanted to continue the 
rescue and see if the other drive would be more fortunate. That other PC is an 
old on, x86 only and I'm using the version shipped in SysRescCd.org v 9.0.3 
which is ddrescue 1.26

With the exact same invocation of ddrescue which is:

ddrescue -i 3367727104 -s 448985088 -b 2048 -v /dev/cdrom ./DVDVOLUME.iso ./
DVDVOLUME.ddrescue.mapfile

(I started invoking without the -i & -s to until all blocks were tried, and 
then wanted to focus on the specific part I'm interested in by using -s/-i)

I have this error message:

Rescued data in mapfile goes past end of input file.
Use '-C' if you are reading from a partial copy.

What is happening? Is this a bug?

Regards
Fab