Why doesn't IBMtape appear in the device path for all of my LTO-4 tape devices?

I am having an issue when generating the device tree in Solaris 10. When the path is created with a small number of drives (in this case 2) IBMtape@... appears in the device path like this:
lrwxrwxrwx 1 root root 78 May 13 20:06 0st -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1:st

However, when the device tree is created with 60 drives attached st@... shows up in the device path for 58 out of 60 LTO-4 tape drives.

In the two drive scenario, the media changer and one drive are on VTL port 0a while the second drive is on VLT port 0b. When I create the device paths IBMtape@ &.. shows up in the path.

When I perform the same steps with 30 drives assigned to each port st@ &.. is in the device path. At first glance you would think that the st driver has taken over those devices. Yet a long listing shows the major number is 305. The number 305 is assigned to the IBMtape driver in /etc/name_to_major. I just dont understand the inconsistency in the device path. Does it really matter as long as the driver is IBMtape (305)?

Here is what I currently see:

[root@v240 /]# grep IBMtape /etc/name_to_major

IBMtape 305

[root@v240 /]# ls -l /dev/rmt/*|grep st|wc -l

480 <-- this number equates to the 8 entries created for each of the 60 LTO-4 tape drives.

Here is an example path:

lrwxrwxrwx 1 root root 73 May 14 02:32 /dev/rmt/0st -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/st@w510a09820001922c,1:st

NOTICE the major number is 305 (see below)

# ls -l /devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/st@w510a098

crw------- 1 root sys 305, 1937 May 14 02:38 /devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/st@w510a09820001922c,1:st

All of the device paths look like this with the st@ except for two drives  29st & 59st:

[root@v240 /]# ls -l /dev/rmt/* |grep IBM

lrwxrwxrwx 1 root root 79 May 14 02:32 /dev/rmt/29st -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:st

lrwxrwxrwx 1 root root 80 May 14 02:32 /dev/rmt/29stb -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stb

lrwxrwxrwx 1 root root 81 May 14 02:32 /dev/rmt/29stbn -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stbn

lrwxrwxrwx 1 root root 80 May 14 02:32 /dev/rmt/29stc -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stc

lrwxrwxrwx 1 root root 81 May 14 02:32 /dev/rmt/29stcb -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stcb

lrwxrwxrwx 1 root root 82 May 14 02:32 /dev/rmt/29stcbn -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stcbn

lrwxrwxrwx 1 root root 81 May 14 02:32 /dev/rmt/29stcn -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stcn

lrwxrwxrwx 1 root root 80 May 14 02:32 /dev/rmt/29stn -> ../../devices/pci@1e,600000/SUNW,qlc@3,1/fp@0,0/IBMtape@w510a09820001922c,1e:stn

lrwxrwxrwx 1 root root 77 May 14 02:32 /dev/rmt/59st -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:st

lrwxrwxrwx 1 root root 78 May 14 02:32 /dev/rmt/59stb -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stb

lrwxrwxrwx 1 root root 79 May 14 02:32 /dev/rmt/59stbn -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stbn

lrwxrwxrwx 1 root root 78 May 14 02:32 /dev/rmt/59stc -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stc

lrwxrwxrwx 1 root root 79 May 14 02:32 /dev/rmt/59stcb -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stcb

lrwxrwxrwx 1 root root 80 May 14 02:32 /dev/rmt/59stcbn -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stcbn

lrwxrwxrwx 1 root root 79 May 14 02:32 /dev/rmt/59stcn -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stcn

lrwxrwxrwx 1 root root 78 May 14 02:32 /dev/rmt/59stn -> ../../devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stn

NOTICE the major number is 305 (see below):

#ls -l /devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a

crw------- 1 root sys 305, 3332 May 14 03:09 /devices/pci@1e,600000/SUNW,qlc@3/fp@0,0/IBMtape@w510a09800001922c,1d:stn

The st driver in /etc/name_to_major maps to 33.

I think everything is correct, but I dont understand why the device names are inconsistent.