If you are importing Leads that already exist in your base, you can choose to record conversions for new Leads. This way, only new Leads in your imported list are going to be recorded as conversions. Meanwhile, Leads that already existed in your base will simply have their information updated.
However, RD Station Marketing requires that every Lead must have at least one conversion recorded in their timeline, because this is where Lead entry date and origin are stored. Thus, all Leads that do not yet exist in your base will have a conversion recorded following the import, regardless of the option you select.
It is important to note that these conversions will be accounted for in your reports and in your dashboard, so be careful to make sure an import of existing Leads does not pollute your data.
If you choose to record conversions for all Leads, you can select the date that will be recorded so that it accurately represents the moment you acquired the Lead. For example, if you acquired these Leads from a campaign carried out 2 months before, you can select the date when the campaign was run and your data will be accurate.