If you want an Arch. course in IIT KGP or IIT Roorkee , then only you have to clear JEE Main Paper 1 & 2 and then JEE Adv. Then there will be an Architecture Aptitude Test which is required for admission into IIT Arch. program.

But if you want admission into colleges other than IIT , you have to appear only for JEE Main Paper 2 . Refer to following links for more information: 

http://www.architecturedesigncareers.com/157811378

https://www.toppr.com/bytes/jee-paper-2-syllabus/