I know that most products work via WMI and simply report what they see.
This might cause problems in that the PC's manufacturer might get reported as Dell, Dell-UK, Dell(UK) etc. This will get even worse with software when there are different versions, file names, sizes etc for the same application. Do you know if LANDesk can homogenise these variations and report all the PCs as being from a single manufacturer (ie Dell)? Are these variants stored in the database ??
In hardware it is pretty good that the vendors stick to the right names for themselves and also the models. So while occassionally the scenario you describe will exist it is not as common as in software. LANDesk gives a feature called 'Aliasing' within software license monitoring to deal with this exact scenario and it allows you to standardise the names.
If you do have issues within other areas of the inventory, Managed Planet's Data Translation Services product is excellent for normalising of data.