I had some problems when using switch user in KDE4. Some investigation shows
that I (first user) was at vt:8 instead of the default vt:7. When I logged in
as another KDE user, I found that she was at vt:7....
On the forums, a more expert user suggested that Plymouth may be the cause, so
I booted with plymouth.enable=0 and sure enough, the 'seats' were allocated as
normal.
Here is the thread:

https://forums.opensuse.org/showthread.php/501821-Switch-user-When-did-this-change

here is a (I hope) relevant snippet booted as normal:
linux:~ # cat /var/log/Xorg.0.log |grep -C 5 "VT"
[     6.174] (II) Module nvidia: vendor="NVIDIA Corporation"
[     6.174]    compiled for 4.0.2, module version = 1.0.0
[     6.174]    Module class: X.Org Video Driver
[     6.177] (II) NVIDIA dlloader X Driver  304.123  Wed Jul  2 11:01:29 PDT
2014
[     6.177] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs
[     6.178] (++) using VT number 8

[     6.186] (II) Loading sub module "fb"
[     6.186] (II) LoadModule: "fb"
[     6.187] (II) Loading /usr/lib64/xorg/modules/libfb.so
[     6.193] (II) Module fb: vendor="X.Org Foundation"

Here is the whole Xorg.0.log
http://paste.opensuse.org/52414761

And here the snippet booted with plymouth.enable=0
linux:~ # cat /var/log/Xorg.0.log |grep -C 5 "VT"
[  1194.446] (II) Module nvidia: vendor="NVIDIA Corporation"
[  1194.446]    compiled for 4.0.2, module version = 1.0.0
[  1194.446]    Module class: X.Org Video Driver
[  1194.446] (II) NVIDIA dlloader X Driver  304.123  Wed Jul  2 11:01:29 PDT
2014
[  1194.446] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs
[  1194.446] (++) using VT number 7

[  1194.453] (II) Loading sub module "fb"
[  1194.453] (II) LoadModule: "fb"
[  1194.453] (II) Loading /usr/lib64/xorg/modules/libfb.so
[  1194.454] (II) Module fb: vendor="X.Org Foundation"
And the whole log:
http://paste.opensuse.org/75391735