Crossing "diamond" angles of anything other than 90-degrees get into the area of being "custom made" and are more expensive. The prior diamond may have been brought in from another location as a temporary fix for the location and may have been either a true 90 from somewhere or a custom that had a temporary swing to make it work. In my RR days, we had a big problem on the WP where we crossed the SP at Binney Jct. in Marysville. The WP was responsible for maintaining the diamond since the SP was there first. [A sad factoid about crossing diamonds is that the company who has to do all of the maintenance and buy the replacements is almost always the one the does not dispatch the interlocking.] During the late 70's/early 80's, we had a diamond in there that had been ordered with a slightly bad angle. The SP track is on a very slight curve through the plant--slight enough that it was actually tangent accross the diamonds with no transition spirals necessary. We had to line the SP side perfectly and throw the error into the tangent WP side. The error in angle was so slight that it was barely noticable with the naked eye, but showed up good in a survey transit. The WP trains would hit the "error" and attempt to straighten it out. The result was some badly cracked inserts that were constantly being welded on. In '84, we did a VERY tight survey to get the angle correct for the next order.
With a situation like Grand Junction, there would have been 3 diamonds with a different maintenance responsibility on each one. Somebody didn't have to do anything on any of them, somebody had 1 and somebody had 2.
The WP/ATSF crossing at Stockton Tower also had an interesting agreement. A WP train heading RR west towards the yard crossed 3 diamonds within about 50 feet. The first was the ATSF main, then the ATSF siding/Lead, then an ATSF/SP interchange. The Santa Fe was there first, so the WP was responsible for the Main/Main diamond. The ATSF then added their siding so that was theirs. Then, the SP came in with the interchange so that one was theirs. Only the SP's was a custom angle.
When Oakland Yard (WP) yard got re-built in '78, changes in the area of the old roundhouse eliminated the old balloon track in favor of a wye. The new east leg of that wye now had to cross a lead into Schnitzer Steel. The alignment of that track was tweaked during the design to be able to utilize a second-hand diamond that wes getting too worn for mainline use, but fine for 2 light-use tracks. That diamond was from the old crossing of the SP main and the tidewater Southern right under the Highway 99 overpass in South Modesto, CA.