Same here :
$ ps -edf f | grep xfdesktop | wc -l
18

See attached log.

Also :
$ ls -l ~/.cache/sessions
total 60
-rw-r--r-- 1 user user     0 2008-10-25 17:45 Thunar-117f000101000122494950000000072860002
-rw-r--r-- 1 user user 15942 2009-04-24 08:38 xfce4-session-delphine-laptop:0
-rw-r--r-- 1 user user 14838 2009-04-24 08:36 xfce4-session-delphine-laptop:0.bak
-rw-r--r-- 1 user user     0 2009-01-19 08:04 xfwm4-117f000101000122495007200000119480000
-rw-r--r-- 1 user user     0 2009-04-12 12:33 xfwm4-20978859f-6a4d-4dca-b967-e9f939fa5e71
-rw-r--r-- 1 user user   531 2009-02-21 17:19 xfwm4-2191852ac-74a8-40dc-bd8c-ce390e568f86
-rw-r--r-- 1 user user     0 2009-04-13 10:11 xfwm4-236112b70-5833-41e6-baf7-ec6d2ed94687
-rw-r--r-- 1 user user   736 2009-04-11 06:59 xfwm4-23ce70605-52c5-46af-98b7-d99307525d36
-rw-r--r-- 1 user user     0 2009-04-12 18:02 xfwm4-24ffaa300-a8fd-407d-bb3b-06ffe5f14d47
-rw-r--r-- 1 user user     0 2009-04-13 09:44 xfwm4-274440c52-d190-4019-9bda-3d368e939f13
-rw-r--r-- 1 user user     0 2009-04-24 08:36 xfwm4-27f495a78-e6c9-4c3d-b15e-9a942830edac
-rw-r--r-- 1 user user     0 2009-04-12 16:27 xfwm4-28962b178-f7b9-425f-b5db-f16975b2a5c2
-rw-r--r-- 1 user user   646 2009-04-11 22:09 xfwm4-297ce95b9-3029-4f92-b2db-617e4d08ea46
-rw-r--r-- 1 user user     0 2009-02-21 23:41 xfwm4-29f3d6ede-1c5b-4f36-94ac-1e6f3eca2b6f
-rw-r--r-- 1 user user   531 2009-04-24 08:38 xfwm4-2a03e8166-57e7-44ff-b8ca-47bfe5a485ba
-rw-r--r-- 1 user user   362 2009-02-22 09:41 xfwm4-2b1de07a0-ef84-4763-a283-2269c42eee54
-rw-r--r-- 1 user user     0 2009-01-19 08:51 xfwm4-2cce8ed75-63f3-4240-8e53-344fd6d4f71b
-rw-r--r-- 1 user user   867 2009-04-18 08:10 xfwm4-2deb52720-6c27-48fc-9035-78469db86e81
-rw-r--r-- 1 user user     0 2009-04-12 11:08 xfwm4-2e19b09f0-0084-407b-b9b3-638a48593dbc
-rw-r--r-- 1 user user  1134 2009-04-12 15:47 xfwm4-2e7b55c0d-0092-42e7-a03e-4f3b79c52404
-rw-r--r-- 1 user user     0 2009-04-12 13:54 xfwm4-2f33510d3-6442-4ee0-ae4a-ffce86f59bf5

$ rgrep -c xfdesktop ~/.cache/sessions/
/home/user/.cache/sessions/xfwm4-2cce8ed75-63f3-4240-8e53-344fd6d4f71b:0
/home/user/.cache/sessions/xfwm4-2e7b55c0d-0092-42e7-a03e-4f3b79c52404:0
/home/user/.cache/sessions/xfwm4-2a03e8166-57e7-44ff-b8ca-47bfe5a485ba:0
/home/user/.cache/sessions/xfwm4-28962b178-f7b9-425f-b5db-f16975b2a5c2:0
/home/user/.cache/sessions/xfwm4-297ce95b9-3029-4f92-b2db-617e4d08ea46:0
/home/user/.cache/sessions/xfwm4-29f3d6ede-1c5b-4f36-94ac-1e6f3eca2b6f:0
/home/user/.cache/sessions/xfwm4-117f000101000122495007200000119480000:0
/home/user/.cache/sessions/xfwm4-20978859f-6a4d-4dca-b967-e9f939fa5e71:0
/home/user/.cache/sessions/xfwm4-2b1de07a0-ef84-4763-a283-2269c42eee54:0
/home/user/.cache/sessions/xfce4-session-delphine-laptop:0.bak:51
/home/user/.cache/sessions/xfwm4-23ce70605-52c5-46af-98b7-d99307525d36:0
/home/user/.cache/sessions/xfwm4-2deb52720-6c27-48fc-9035-78469db86e81:0
/home/user/.cache/sessions/xfwm4-2e19b09f0-0084-407b-b9b3-638a48593dbc:0
/home/user/.cache/sessions/xfwm4-2191852ac-74a8-40dc-bd8c-ce390e568f86:0
/home/user/.cache/sessions/xfwm4-236112b70-5833-41e6-baf7-ec6d2ed94687:0
/home/user/.cache/sessions/xfwm4-274440c52-d190-4019-9bda-3d368e939f13:0
/home/user/.cache/sessions/xfwm4-24ffaa300-a8fd-407d-bb3b-06ffe5f14d47:0
/home/user/.cache/sessions/xfwm4-2f33510d3-6442-4ee0-ae4a-ffce86f59bf5:0
/home/user/.cache/sessions/xfwm4-27f495a78-e6c9-4c3d-b15e-9a942830edac:0
/home/user/.cache/sessions/Thunar-117f000101000122494950000000072860002:0
/home/user/.cache/sessions/xfce4-session-delphine-laptop:0:51

Hope this helps.