100499 (1996 XP) and 2014 OT426

 Backward integration with Mercury6 based on nominal orbital parameters:

)---------------------------------------------------------------------
) Important integration parameters:
)---------------------------------------------------------------------
 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS
 start time (days)= 2459671.5
) stop time (days) = 102458000.5
 stop time (days) = -1d8
 output interval (days) = 100
 timestep (days) = 0.05
 accuracy parameter=1.d-12

Result

 P.S.

Following a comment from Afrien Coffinet (what happened at about year -15000 ?), I plotted the orbital parameters of the asteroids that are almost overlapped, at least at the scale of the graphics.

Around that date: 

• eccentricity reached the minimum value as confirmed by q and Q, 
• inclination reached the minimum value, 
• the argument of perihelium had a "disturbance" (encounter with a big planet? - not clear)
  
• the ascending node reached the maximum vaue)