I'm not sure what you mean by prototype disklabels.  But the simple
answer is yes.  The ioctl, 
	case DIOCGDINFO:
		*(struct disklabel *)addr = *(wd->sc_dk.dk_label);
		return 0;
returns your "active" label.  While
	case DIOCGDEFLABEL:
		wdgetdefaultlabel(wd, (struct disklabel *)addr);
		return 0;
returns probably what you mean when you say prototype disklabel.
(scsi sd code is isomorphic to the above.)

Todd Whitesel <toddpw@best.com> writes:

> Do prototype disklabels stick around indefinitely or are they replaced by
> data from the disk on the first disklabel -r ?
> 
> Todd Whitesel
> toddpw @ best.com