Two domain names..one site...what would you do?
 

I have a databas driven website I will soon launch. I have two domain names that I want to be exactly the same.

I was going to 301 one of the domains to the other, but it will forward the name over. I want the domain name to stay what it originally was typed in as.

Example: go to www.xyz.com would bring up www.abc.com..but keep the address in the browser as www.xyz.com.

I know I can:
1. Use the same php on both domains to look the same.
a. Issue...won't search engines not like this?
2. I can 301 one of the domains and say fuckit...it forwards to another domain and I will deal with it.
3. I can frame forward one of the domains.
4. I can have my httpd.conf file point to the same files for both domains.

What would you guys do?

Why not just have two seperate websites with identical content? If it's database driven, just access the same database and everything will be peachy, right? I'm a layman when it comes to these things though.

that's what i was gonna say.

Will search engines penalize me for this or just ignore one of them..or do nothing?

Just cut your website in half, i hear they will grow new ends and continue life as normal. Like a worm.