Short answer is no, there will be no damage to you camera from running the wrong firmware... The developers and testers here have run many versions of early testing code and "crashed" there cameras without any word of "bricking" any camera (that I have ever read here). (for the non-English or beginners with computers--"crash" in terms of the software failing, and "bricking" as in turning your camera into a brick--i.e., useless).
If the 1.01b code works on your 1.01a camera--that is good news. I think there is a thread here where they are porting CHDK to the 1.01a. There is at least one other Canon camera where two different firmware versions both work with the same CHDK...
If you want an explanation of how come--Think of a book with a table of contents. The firmware is a series of pages of different software functions. Each one starts with its own page number (address).
Now, think if the table of contents were ripped out of the book, and instead of the firmware referencing the "Table of Contents name", each piece of code just says "jump to page number xxx". That works just fine in the camera, because every piece of firmware knows where every other piece is at.
However, to run CHDK, it needs to know the "page number" (address) of each of these chapters so that it can "jump" to the right page and run the correct piece of code.
Since there is no "table of contents" in the camera firmware, people have to dump the firmware and search through the code and identify each starting address and what that piece of code does (focus, take a picture, etc.). That is the long, difficult, and boring part of porting CHDK.
So, in the end, each version of CHDK is very similar, with just "hard coded" with the addresses (page numbers) of each major software function for any particular model of camera.
I did a quick search and found the thread where this question was discussed:
SD700 IS firmware 1.01a.....is there any hope for me using CHDK?And it was found that the firmware for SD700is v1.01a and v1.01b is identical (except for the time and version number--apparently). So CHDK for v1.01b will work just fine on v1.01a...
Hope this helps.
-Bill