There is currently no simple built in way to synchronise two Sonic Pi instances.
Several tools exist that have attempted to allow such a thing, and they may have worked at one point, but it is quite possible they no longer work.
The following posts have a few more details:
It is definitely something that the core team would like to support natively, and to that end some initial groundwork has been laid. However, there is still much that needs to be done to implement it, and it boils down to a question of priorities vs available resources. We definitely want to see this feature end up in Sonic Pi though
