The sign of a good search is that some of the same relevant results come up in all your searches. The databases content does often overlap and this is useful to reassure you that you are replicating your search as consistently as possible across all your sources. If you get the same results these will be de-duplicated at a later stage (see the 'Managing your references' section).
After you have transferred your search to all the databases and sources that you want to cover, the next stage you need to take is to verify your search. This means that you need to check if your research has retrieved the key documents that you found back in the scoping process in step 1?
In order to validate your results and check that you haven't missed anything, you could also do the following searches at this stage:
If you find some articles that are missing from your search ask following questions:
Depending on the answers that you find, you may need to go back and re-tweak your Full Search Plan and re-run some of your searches.