What's Wrong With 2 Front Door Locks Both Used With The Same Key?

[AndiFlatland]

I live in a multi-occupied house, and years ago we had a problem with break-ins - 3 in 12 years. So we all put cash together to have a second deadbolt lock fitted. But the girls kept losing their keys and having their handbags nicked. The last time this happened, the landlords changed both locks, but replaced them with 2 locks that could be accessed with the same security key. (One of the locks is an ordinary Yale-type, while the other has a narrow protruding barrel on the outside, and a turn-knob to lock and unlock it on the inside).
I've always felt that there's something fundamentally wrong with this, but I can't quite work out what it is. Other than if the key was lost but the finder knew which address it belonged to, he was in with one key without a problem.
Personally, I felt it was just another example of the landlords saving money by doing everything on the cheap, as usual.
Any further views on this would be welcome, as I'm about to take the landlords to court for continual neglect of the property and refusing to carry out essential maintenance, and I want to throw this one into the mix when the time comes.

[Old_Geezer]

So one only needs a single key to get in. Doesn't sound massively beneficial over a single lock, to me.

If going to court, might this not be better in "law" ?

[Roddyspidercreat]

Presumably if someone lost the front door key, they would loose all on the key ring so this is not a security risk but done for your convenience, less keys on ring, don't have to fumble in dark for right key for right lock. It usually costs more to have locks keyed alike, so, basically what he's done is all positive.. I'm a locksmith..