No combining of up-down scans (see section 8.3.6) is carried out by the SPG pipeline . This is because the up part of the scan may have a different zero level from the down part, or a line may have a different shape in the two scans, both due to memory effects (see section 5.5). Also, one of the up-down scan pair may have been affected by a `scan jump', ref section 5.4.
Users should check the two scans of their data to ensure features are present in both and that the scans are not behaving differently. If they do behave differently care should be taken analysing the data and in some cases it may be necessary to throw away any affected data.
Assuming up-down scans are present in your data and both scans are similar, you can either attempt to get the information you want (e.g linewidths) from each scan individually, or combine the scans then get the information.