Our iMac seems to be running on two systems??

Question

Sorry if i am not explaining this very well, I am not sure of the correct terminology.  When we upgraded to Yosemite we have had a couple of problems.  We lost all our photos from iphoot, tried many suggestions and spoke to Apple but they are unable to help.  That is fine.   The other day we had a power cut when we were out.  My husband got power back on but I noticed when we switched mac back on where it normally says the "hall's iMac" it now says "the hall's iMac (2)" .  I wondered if it was in some sort of recovery mode.  I logged out of our account and at the screen where it gives you the option to log back in under your own or guest account, Inoticed in the top right hand corner it said in red writing "safe boot".  I thought best to shut down and completely restart the iMac, which i did and safe boot has gone but it still seems to be in some sort of second system or safe system as it still has the (2) after the name of our mac.  Sorry if I am confusing, I don't know how else to explain.  wondering whether to completely reset to factory settings and re-load yosemite again? there isn't anything on the iMac that we could lose, have got all our docs on a pen drive and we don't have much else on it.  If anyone has any advise, we would much appreciate!

Answer 1

There are several possible causes for this behavior.
1. Two (or more) computers on the local network have the same Bonjour name, such as "X's-MacBook-Pro.local". Resolve the name conflict by renaming one or more of them in the Sharing preference pane.
2. You have two simultaneous connections to the same local network: probably Ethernet and Wi-Fi. If applicable, disconnect the Ethernet cable or turn off Wi-Fi.
3. A Mac wakes from sleep due to network traffic. This is a bug in OS X that may only affect some models.
4. A device that gets its network address from the router wakes from sleep, and the address it was using before has been assigned to another device.
5. A third-party wireless router has incompatible settings or firmware. In that case, refer to the manufacturer or ISP for support. Restarting the router may help, temporarily.
6. If the router is an Apple device, it may need to be restarted.
7. A third-party Bonjour device on the network is malfunctioning. Finding out which is a process of elimination.
8. There is more than one DHCP server on the network. Typically, there would be two or more wireless access points configured to act as routers.
9. See this support article.
10. Back up all data. Make notes of your settings in the Network preference pane.
Triple-click the line below on this page to select it:
/Library/Preferences/SystemConfiguration
Right-click or control-click the highlighted line and select
          Services ▹ Reveal
from the contextual menu.* A folder should open with an item named "SystemConfiguration" selected. Move the selected item to the Trash. You may be prompted for your administrator password.
Restart the computer and empty the Trash. You will need to recreate the network settings.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select
          Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.