depends on the purpose and set up of the multiple servers.
normally, using multiple servers is for load balancing.
This means that each server is an exact duplicate of the others, when a browser makes a request for your website, the server that has the least traffic on it jumps to fulfill the request.
This means that the assets directory that files are uploaded to exists on all of the servers, when a file is uploaded, it is uploaded to the server that is currently fulfilling the website request, then copied to the others, so that it exists on the other servers as well.
There may be a delay in the copying process, but it should be too long.