After trying for a (long) while to have multiple targets defined on the same host, and having my initiator to see both, the solution what in fact simple: Use different values for the LUN!

Here’s a snippet of /etc/ietd.conf

Target iqn.2010-01.com.test:storage.disk1.sys1.000
        Lun 0 Path=/media/usb/test0.img,Type=fileio,IOMode=rw
Target iqn.2010-01. com.test:storage.disk1.sys1.001
        Lun 1 Path=/home/psq/test1.img,Type=fileio,IOMode=rw

Then don’t forget to restart: “service iscsitarget restart”