Using the same local folder for Dropbox and Skydrive
Solution 1:
I have done some tests with sharing the same folder on different clouds (One Cloud, Google, dropbox,...)lately. To be honest, it seems to give nothing but problems. In fact, the files seem to be in 'sync mode' all the time and the services take a lot of memory resources. I think the reason is the following: one cloud (f.ex. dropbox) sees a new file and starts synchronising. Once done, it seems that something on the folder or file is modified. The other cloud starts syncing as well. Once done, dropbox sees a change in the file and resyncs. But so does the other cloud when dropbox has synced. So both clouds seem to be syncing all the time.
Solution 2:
Cloud services will always timestamp their synch folder on your device with the time of their last synchronisation. How exactly they do this may vary from service to service.
If the synch folder is shared between services, the second service will see the date change of the first service as an update and will then go off and try to synchronise.
This can get you into a deadly embrace situation where everything is synchronising all the time.
I find it easier to have a daily run of robocopy (on Windows) to synchronise the two local synch folders. That does mean that you have two copies of everything on your local system but I have put each service's synch folder on a separate local hard drive so there is additional redundancy.
I haven't tried this on a phone so can't say if this is feasible there.