The lamedb is single source of truth and the only thing that is changed in a service scan by enigma2.
By "change" you mean adding services to lamedb? Surely, service references are not modified simply by doing a service scan?
Given...
1:0:2:E42:1C20:13E:820000:0:0:0
This reference stays the same, even after a service scan? Even if you add some new services to the list (lamedb)? I guess they will be just appended to the end of the file.
Because if this reference is modified (not likely) to something like...
1:0:2:E42:1C20:10E:820700:0:0:0
Then this new reference needs to be added to all bouquets that use it. I guess you can call it downstream update, given that the lamedb is the single source of truth (master). Making changes upstreams, i.e. modifying the reference inside a bouquet would not propagate to the lamedb. In my particular case, what I think happened is, my bouquets contained duplicate references to the same services found in lamedb.