Duplicate slice entries in /dev

I'm running -CURRENT from about a week ago, and have noticed that
duplicate entries are showing up in /dev before a slice is mounted.
For example I created a swap-based md disk, used fdisk to write a
partition table containing a single msdos partition and noticed that
two /dev/md0s1 entries existed.  Today I've just got a new microSD card
connected via a card reader.  I created a filesystem on /dev/da0s1 and
I see the following:

tau# fdisk /dev/da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=968 heads=255 sectors/track=63 (16065 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=968 heads=255 sectors/track=63 (16065 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 63, size 15550857 (7593 Meg), flag 80 (active)
	beg: cyl 0/ head 1/ sector 1;
	end: cyl 967/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>
tau# ls -l /dev/da0*
crw-r-----  1 root  operator    0,  85 Feb 12 12:28 /dev/da0
crw-r-----  1 root  operator    0,  86 Feb 12 12:28 /dev/da0s1
crw-r-----  1 root  operator    0,  86 Feb 12 12:28 /dev/da0s1
tau# mount /dev/da0s1 /mnt
tau# ls -l /dev/da0*
crw-r-----  1 root  operator    0,  85 Feb 12 12:28 /dev/da0
crw-r-----  1 root  operator    0,  86 Feb 12 12:28 /dev/da0s1
tau# umount /mnt
tau# ls -l /dev/da0*
crw-r-----  1 root  operator    0,  85 Feb 12 12:28 /dev/da0
crw-r-----  1 root  operator    0,  86 Feb 12 12:28 /dev/da0s1
crw-r-----  1 root  operator    0,  86 Feb 12 12:28 /dev/da0s1

-- 
Bruce Cran