Yes, that is definitely a risk of doing this. Does the benefit of it counter the risk of having to start a couple days earlier? I am good with whatever majority wants. Doing the replacement allows us to not have to worry about additional picks mid-draft or post draft.
I do see the concern of the potential of two close teams at the regular season like Arizona and St. Louis
From previous playoff drafts, this is a pretty conservative group. And no one is going to take a huge risk on either Arizona or St. Louis until later in the draft. And by that time the regular season will almost be done and we should hopefully have a pretty good idea which team of St. Louis or Arizona is going to make the playoffs. Ideally when these players are being picked the regular season only has one or two games left. At this point it will likely be Team B HAS to win two games to make playoffs and Team A has to lose one of the final two games for Team A to make playoffs.
So if we think the replacement players should not be picked at the same time as the original pick. Then we have to allow for another day or two at the end of the draft to ensure that there is sufficient time to make the additional/replacement picks.
The main benefit of the replacement options being picked at the same time is that the draft would be able to be completed in shorter time frame. as we would not have to wait for someone to make their replacement picks whether it is mid-draft (when team is mathematically eliminated) or end of draft.