You can have more than one tag in a single .aspx page but only one tag will have runat="server" attribute.

Use a frameset if u want both the forms visible at a time...

you can have multiple form tag in a asp.net page but one thing keep in ur mind that only one tag should be visible at a time the other will be invisible. so you need to use a asp.net server control like panel and place ur form tag there and make it invisible then it will not throw any kind of error.