Your problem is the adjustment Equalizer in the carrier must be removed if you are using green bearings without adjusters or after putting one side in the other axle won't go in all the way.
Put one axle in without the nuts. Then install the other one you'll see It will push each other out.
The easy fix is to cut the axles so they don't bottom each other out. If you already tightened them you probably already damaged the retaining plates on the axles.
Measure the distance that the axles push each other. Split the difference and cut that much off each axle. Cut it 1/16 extra for clearance
On a Clutch style unit there are equalizer pins that can be removed they are connected with a roll pin. Cone style and open carriers the rear has to come apart.