Auction don't prevent bidding on another private once the "Plug is pulled"

[McDood]

I had 2 players with bids on the second private, once the first was bought, one of the player with a bid a 2nd private did his bid on another private (which I don't think is allowed in the rules)

(The log is inverted when I copy paste it)

3 collects $5 from Mitsubishi Ferry
1 collects $5 from Takamatsu E-Railroad
-- Operating Round 1.1 --
3 passes
2 passes
3 buys Mitsubishi Ferry for $40
1 passes
1 bids $60 for Sumitomo Mines Railway
1 buys Takamatsu E-Railroad for $20
3 bids $70 for Dougo Railway
2 bids $65 for Dougo Railway
1 bids $85 for South Iyo Railway
3 bids $40 for Mitsubishi Ferry
2 bids $55 for Sumitomo Mines Railway
1 bids $35 for Mitsubishi Ferry