This question occassionally comes up.
OUT OF THE BOX
There is no "Out of the box" way to limit the number of web sessions that a user may initiate.
ENHANCEMENT REQUEST
There is an Enhancement Request lodged for this feature to be added. If this is a concern to your site, you may log an issue with Support requesting this Enhancement Request also. The more customer sites request a feature, the more weight the request may receive. Please include the "Business Reason" about why this is a concern. What benefit is gained by restricting to one user login?
CAT SERVICES CUSTOMISATION
An alternative is to discuss with CA Technologies, Services, about implementing a feature which meets your business needs. For example, having users create requests via Web Services. Or getting a script to monitor pdm_webstat -D output for duplicates and sending a notification. There are a number of alternatives.
BUSINESS CASE
It really depends on why this functionality is needed. Can you expand on the business reason for why this is needed?
Allowing multiple logins does allow some benefits.
Some reasons given prior by clients:
* Licence count: This may be overcome by doing a pdm_webstat - D and removing duplicates to get an accurate count.
* Performance concerns: Having multiple logins by users rarely causes performance concerns, as the users are still only capable of updating one screen at a time. Plus in general Service Desk scales well.
* "Neatness": Enhancement could be made to either (a) alter the pdm_webstat output to only give 'unique' counts or enhancement could be made to only allow single login.