Match selected object names by their symetrical position across X. If L_arm matches R_leg, L-arm -> L_leg.

mirror_names.py

import maya.cmds as mc

eps = 1E-5

sel = mc.ls( sl=1 )

while sel:
	
	v = mc.xform( sel[0], q=1, rp=1, ws=1 )

	for s in sel[1:]:
		
		vo = mc.xform( s, q=1, rp=1, ws=1 ) 

		if abs( v[0] + vo[0] ) < eps and abs( v[1] - vo[1] ) < eps and abs( v[2] - vo[2] ) < eps:
			mc.rename( s, s[:2] + sel[0][2:] )
			sel.remove( sel[0] )
			sel.remove( s )
			break