I'll pass along what I know on this, but I need to clarify what you are asking first too.
Are asking, can the one side the tech replaced be a 25 1/8" and the other, you will replace with a 25 1/4" long "unloaded" eye to eye length be OK?
If that is what you are asking, the answer would be no in my opinion. You would negatively affect/change the thrust angle of the axle to the tow ball to be beyond tolerance. I'll explain a little.
For proper axle alignment to have the trailer track straight ahead with the body of the camper, the dimension from the center of the tow ball to a "place" where the wheel mounts to the axle on the left side, needs to be the same from the tow ball to the same "place" where the wheel mounts to the axle on the right side within a tolerance.
See this sketch I made, this is on tandem axle and yours is single axle, but the front axle has the same needs. The tolerances are what I received from Dexter axle.
Since the main leaf spring mounts to the front spring hanger, the leaf spring distance from the hanger bolt to spring pack center pin creates the center of the wheel on each side. The center pin in the leaf spring pack aligns to the axle seat. While the 1/8" eye to eye would result in 1/16" at the spring center pin distance, the wheels could be more then the 1/16" off on purpose by using the different length springs as there is other error in the system already. The hangers are not welded on "exactly" the same on the left and the right, the excess play in the axle seat hole to the spring pin can be shifted against you, and then you intentionally added in a 1/16" offset and you can be way out of tolerance. The tires will wear prematurely and the camper may dog track to one side when towing.
Since trailer axle alignment is poor to start with on an RV in many cases, I would not introduce on purpose known error the entire recommended tolerance from the start.
I looked quick and they do make the 25 1/8" eye to eye. BUT you have to confirm the spring arch height is the same as the other spring and that the tech did not make a mistake and it was not a 25 1/4" spring.
https://www.etrailer.com/Trailer-Leaf-Spring-Suspension/Universal-Group/SP-212275.htmlNOTE: The arch height is normally measured from the center of the eye to the surface of the main leaf at the center. But some web sites are showing the arch height at the top of the center pin which I feel is not accurate.
Ideally go back to the tech and get the same brand and spring they put in. Also, check the axle weight and each wheel to make sure you are not over weight which may have caused the first leaf spring to fail.
Hope this helps
John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.