[sijoc]

Are they the same case (obviously pushers on opposite sides)?

103 shot from my singular collection ;-)

EZM shot from www.broadarrow.net

 

[gra]

my guess is 103 & 503 pretty much uses the same case with some variations

 

[ferdinand]

Caseback would be different, of course, but apart from that, they are likely to share the same case.

 

[Rafael_T]

I doubt they use the same case

As the Valjoux 7750 and the Lemania 5100 have the pushers in different positions relative to their respective crowns.