http://www.lifestohack.com/how-to-dual-boot-multiple-roms-on-your-android-smartphone/
Android Tutorial, How to February 11, 2014
Note: This tutorial assumes that you already have a knowledge for flashing ROMs and that you have a supported phone which is already rooted. For the list of supported Smartphone please refer the list at the end of this tutorial.
Related Topic: Advantages and Disadvantages of Rooting Android Phones. How to Root Android Phones?
First of all download all the ROMs that you want to install on your android smartphone. CyanogenMod, AOKP and there are many more to choose from. Don’t forget to download the Google apps also. Google apps does not come installed with the Custom ROM, so you have to manually flash it. After downloading both ROM and Google app, copy it to your SD card.
Step One
I will repeat this each and every time, but I will never get tired: Please back up your current ROM. Nobody knows what will happen when flashing ROMs, if everything goes good that is nice but if anything goes bad that you should have a recovery option.
Step Two
Download and install Boot Manager from the Google Play, there is paid and free version, get the one you want. Boot Manager is Android’s first multi-boot application. It allows you to install and boot ROMs from your sdcard and boot between then with just a reboot. The application acts as your recovery for your sdcard slots.
Step Three
When the Boot Manager is installed than click on it to open the app for the first time. It will ask you to back up your boot.img and I really recommend you to do so. After that Go to “Install ROMs” and choose the ROMs(Zip file) that you downloaded and copied to the SD card. Select all the boxes Wipe Data, Wipe System and Wipe Cache. Note that When you are installing new ROM you have to select these option all the time.
ATTENTION!!! Please Do not boot now into the ROM.
Step Four
It will take some time, when it finish flashing the ROM click on “Done”. We have to install the Google apps also. Go back and click on “Install ROMs” and choose the Zip file of the Google apps and a dialog will then display asking which slot to install it to use. Use the same slot that you used before for that Specific ROM that you are trying to install Google apps for. You don’t need to select the boxes for Wipe Data, Wipe System and Wipe Cache this time. You do the same thing if you want to install any themes. But if you want to install the Kernels than first you have to do the same thing as installing the Google apps but after choosing the Kernel file select the fifth button on the install screen which reads “Install Kernel”.
Step Five
You are at the end. If you are successful with all the steps above than I would like to congratulate you. You made it through the though steps. Now it is really simple. You just need to boot into the ROM that you want to use. Go back to the Boot Manager and click on “Boot Installed ROM”. There you can see the list of the ROMs that you have installed. Just select the ROM that you want to boot into and your device will reboot to that ROM.
Don’t worry the Boot Manager will be installed automatically on the ROM that you are booting into. You just have to go to Android Market and sign in. You can install upto five ROMs in this way. So what are you waiting for, head towards Google Play and get it.
Download Boot Manager | Free | Pro
List of Supported Device
If your device is not supported you can submit the Unsupported Device for Boot Manager here.