There are 4 hud channels for hud messages. The last parameter of set_hudmessage is the channel and you set it to 1. So it is overwriting the last one displayed. If you do not specify (or set it to 4) it will select the next available hud channel.
Though my suggestion would be to combine all the strings into one string (each string separated by a new line ^n) and show the one string. This way you would only be using one channel instead of all 4 channels.