In reply to Toerag:
> Hi Jim,what's the logic behind this configuration? Why not just have the two bolts level with each other, or directly above each other?
There are a number of reasons.
Two bolts level with each other and directly threaded tend to twist the rope.
At a multi-pitch belay it is nicer to arrange the bolts so the lower one can be clipped with a standard girth-hitched sling as a cows tail and the other a bit higher for those who prefer to bring up the second with either a guide plate or a re-direct.
If the bolts will be (in the future) joined by a chain then with two horizontal bolts you ideally need 2 chains, with them staggered you only need one which is cheaper.
If you are installing chainsets then the range of possible placements when they are horizontal is very limited, with the inline system it is vastly greater.
When the bolts are horizontally installed and used threaded direct the wear on each bolt is equal, therefore when one becomes dangerous the other is also dangerous, with an offset installation one bolt becomes dangerous when the other is still safe.
Finding a suitable location to install two bolts horizontally is often not so easy!