Some days ago I cloned my /dev/sda1 partition with clonezilla in partition-to-partition mode to /dev/sda3.
It worked, but now that I've finished the setup of system in /dev/sda3, I wanna reinstall /dev/sda1 for other stuffs.
This partition is NOT mounted, but ubuntu's DISK UTILITY thinks it is, while it doesn't see as mounted the currently active / partition /dev/sda3.

This is the df- TH output :

Filesystem Type Size Used Avail Use% Mounted on
/dev/sda3 ext4 32G 6.2G 24G 21% /
udev devtmpfs 2.2G 13k 2.2G 1% /dev
tmpfs tmpfs 845M 906k 844M 1% /run
none tmpfs 5.3M 0 5.3M 0% /run/lock
none tmpfs 2.2G 115k 2.2G 1% /run/shm
/dev/sdb1 fuseblk 321G 147G 174G 46% /Dati

Gparted instead, sees /dev/sda1 as NOT mounted (checked with Information option), but it display the BOOT flag on this partition, while the real booted partition /dev/sda3, hasn't it.
If I try to format the /dev/sda1 partition, it gives me this error :

GParted 0.8.1 --enable-libparted-dmraid

Libparted 2.3
Format /dev/sda1 as ext2 00:00:02 ( ERROR )

calibrate /dev/sda1 00:00:00 ( SUCCESS )

path: /dev/sda1
start: 2048
end: 62500863
size: 62498816 (29.80 GiB)
set partition type on /dev/sda1 00:00:02 ( SUCCESS )

new partition type: ext2
create new ext2 file system 00:00:00 ( ERROR )

mkfs.ext2 -L "" /dev/sda1

mke2fs 1.41.14 (22-Dec-2010)
/dev/sda1 is mounted; will not make a filesystem here!

How is possible to correct this behaviour ? Is this due to some lacking option in clonezilla phase ?

TIA Enrico