Could this be the result of two people doing uploads at exactly the same time, down to the millisecond?
In a word.. No. Data is transfered over the net using TCP and UDP. Both data types are routed through routers over the net to their destination, and routers, well, route data. It is possible (and highly probable), that if two people were on the same local network, that both machines could send out data packets at the same time. (This occurs all the time acutally). However, when packets 'collide' the collision is detected, (hence the name Collision Detection with Multiple Access or CMDA), and both sending machines wait a random amount of miliseconds, and resend the packets. millions upon millions of data packets are streaming in and out of LL's many different servers, and the fact that two people doing the same thing (uploading textures in this case) has nothing to do with anything. At the network level, a data packet is a data packet, weather it deals with uploading a texture, joining a group, or walking across the ground, it all looks the same at the network level. At the network level, as well as at higher levels, everything is queued into a buffer, and handled on a one by one basis in all cases.