Physically, the refrigerator, if it has to, should lie on the side on which the compressor is. In your case you have 2, so if it's horizontal, it doesn't matter.
As Stanley wrote *, he has to come off after such transport.
Added after 26 [minutes]: maybe this article will help you, but with 2 aggregates it is either vertical or no difference which side.
http://www.przeprzałkikatowice-24h.pl/transport-agd/