Originally Posted by
corporate-wage-slave
BA's computers can't handle something as straightforward as multi city redemptions, so you will be fine.
Not sure how a redemption comes into play here. Sounds like these are purchased tickets.
I disagree with CWS. I think their system will notice that you're booked on two flights at the same time (and different from irrops, it'll be in the system longer, so a greater chance of some process catching it). I know that there are stories in other airline forums about people in similar situations where they've found one/both of the bookings cancelled by an airline.
Two other ways to look at it:
1) You're costing them revenue. You clearly can't be on two different flights at the same time. So one of those seats is likely to go unsold in the end.
2) They assume the traveler has made a mistake and unintentionally booked conflicting trips. Maybe they contact the traveler, maybe they don't.