Unfortunately, what you are looking for can't be done, at least as far as I know. The only thing I can think of that comes close is having two nandroids, one of CM and one for SR and flash back and forth between the two...

 

Edit: yes it's very possible, the developer is still working out bugs for the latest release:
http://forum.xda-developers.com/showthread.php?t=847423

It may be possible, it's been accomplished on the htc hero:

http://androidcommunity.com/dual-boot-android-to-android-20100506/

Found instructions here:
http://www.androidng.com/dual-boot-android-roms
Haven't personally tried it yet so not sure if the instructions are still relevant. No apps2sd though.

 

I've actually been working on this for a few days. My team (TeamADX) was able to dual boot on the Droid eris [ROM] Dual Rom V1.2 | 2.2CM/AOSP 2.1 Sense in one.... [11/19/2010] - xda-developers so I figured i'd give it a go on the incredible which i now own. My biggest reason is because I do app development and need to test on aosp and sense from one phone. So far I have CM7 and a stock Sense build that will both boot using the internal storage. I personally don't use my internal storage as most apps default to the sdcard so it was sitting blank on my phone. It's also much faster and more stable then using the sdcard. Unfortunately the internal storage also include the partitions for data and cache of a normal rom and the phone will not let you change the partitions on the emmc but it will let you reformat the 6.5gb fat32 partition to ext3. I then had to symlink the data and cache to all use the same partition since I only had one available. It was a little tricky but I think I have it fairly stable. I will need to write a quick app that you can install on both roms that will change to boot.img so that you can boot back and forth between the 2 roms. Feedback would be great for the following things:

1. Is this worth the time to anybody? Would it be something you would give up the 6.5gb's of internal storage for?

2. Before on the eris we had to install 2 roms together and we got alot of people who wanted to "change" one of the roms to thier rom of choice. With the inc I'm able to leave the phone's rom intact so I'm thinking that I should only release the roms that go on the seperate partition and let the user choose thier first rom...comments or ideas?

I should release something on this in the next week or so maybe sooner but would love to know what people think.

 

I personally love the idea and would give it a shot.

 

I'd give it a shot. Putting items on the internal storage is more of a hassle than it is worth from a convenience standpoint.

 

I released the first version of the Dualboot options over on xda if you want to check it out.

[Roms]DualRom-The dual booting solution for Incredible 4-17-11 - xda-developers

 

I have a few questions before I give this a shot.
The ROM stored on the internal memory can only be one of two roms (CM7 and Sense) that you provide. Is that correct?
The one stored on the phone ROM can be any other ROM the user installs. It can be changed by flashing a new ROM and then flashing one of the zips to reinstall the Dualboot program, right?
Thanks.

 

Yes that's right. The rom you choose to put on the actuall phone is up too you. The zip will make minimal changes to it such as adding in the reboot app i wrote to let you boot back and forth. I also added a script in the second post to undue those changes and reformat the internal storage back to storage space as it originally was.

 

Good to know; I will be trying this tomorrow when I have some extra time to give you guys feedback.

 

I had to update zip number 2 so if you've already downloaded it make sure you get the updated one before you flash....thanks for testing and I appreciate the feedback...

 

Just found this on XDA. Looks like some awesome, promising stuff. Definitely keeping my eye on this.