Duplicity downloads old signatures when they are irrelevant for the task in hand?

I wonder why Duplicity is not smart enough not to download old signatures when they are irrelevant for the task in hand?

Doing a standard, last backup restore. There is a full backup made few days ago and a couple of relevant incremental changes.

Instead of downloading last duplicity-full file and it's increments, duplicity starts to pull all signatures since a year ago!
WHY? As they are totally irrelevant for the task requested.

I know I can clean them up, but this is not what I want to do as they are kept in case point in time recovery is needed.

Hasn't the authors thought this simple behaviour or is there a reason it downloads all these old signatures?