Sure.
Step 1 is to "!" to escape to a shell.
An optional Step 2 is to examine your dmesg, which will give you make/model information about the drives; this may indicate physical differences between the drives. Obviously, this won't help if all five are identical hardware. e.g.:
#dmesg | grep wd
Step 3 is to use fdisk(8) to see the MBR partitions assigned to each drive, e.g.:
# fdisk wd0
# fdisk wd1
.
.
If you actually need to mount any of these foreign partitions while running the ramdisk kernel, which you are using for the install, it will depend on the particular filesystem type as well as the specific architecture of your OpenBSD machine -- capabilities of the ramdisk kernel vary by architecture.