clonehd raw image is bigger

[lencoboy]

Hello,
i tried to install a debian distribution following these steps:
1) dd if=/dev/sdc of=image.img (4 gb Compact Flash)
2) VBoxManage convertfromraw image.img image.vdi
3) registered vdi image in VirtualBox, created vm and installed debian in vm (i also used snapshot)
4) VBoxManage clonehd image.vdi image.img --format RAW (vdi of last snapshot)
5) dd if=image.img of=/dev/sdc

last command after some minute of writing, give me "no space left on device"...
i compared the vergin image and the image after the conversion:
4009623552 image.DEBIAN.img
4009549824 image.VERGIN.img

why image.DEBIAN.img is bigger than image.VERGIN.img?

[lencoboy]

i found that VBoxManage attach to raw image extra info. Is it possible to remove those?