I use two devices(PC and iPhone) to browse forum and reply post
Actually the two devices use different network,so I am thinking if this causes IP problem and finally results in banning.
No. You wont be banned for that. I post from a PC and my phone, and you can have as many accounts as you want.
Hey,guy,how do you know that?
How do I know what? The mods/admins have stated several times you can have as many accounts as you want. Posting from different IPs or connections doesn't matter either.
It's true. They also allow people to buy/sell accounts. I dunno why he wouldn't believe there wasn't a maximum number of accounts allowed.
I wasn't sure at first when I signed up. Some forums only allow one account, though I guess it's hard to enforce or police especially with proxies and TOR etc, and that's also one of the main reasons why they allow accounts to be bought and sold as well.
No it won't result in a ban, that's fine.
I often browse the forums on my phone while not at the PC from a different network etc.
拥有多个账号是可以的，也可以同时在不同设备(IP)上登录论坛。
所以大家就不要在说是因为使用多个号而被封号，而要主要自己发帖的内容。 
买卖账号也是合法的https://bitcointalk.org/index.php?topic=604929
