I think it is because you filled the survey twice (once as Steam and once as EGS). In that case, we probably put you on both lists: Expansion pass for EGS and for Steam. EGS expansion passes were not sent out yet. Just a reminder: EGS expansion pass is needed only for the Year One Edition keys from the survey in 2020. The first EGS version from 2019 does not need any additional keys as it already contains a season pass.
You can write an email from your backer email to contact@snapshotgames.com and I will look at your specific case.