you can import the wallet from PC1 to be used in PC2 and they will both show the same amount of bitcoins in your wallet 
By default each PC will have its own wallet address. However, you can import the private key from one wallet so they both have the same address.
https://en.bitcoin.it/wiki/How_to_import_private_keys_v7%2B
https://en.bitcoin.it/wiki/How_to_import_private_keys_v7%2B
That is a bad idea because after you send money from one of the wallets, the two wallets will no longer be in sync and will show different amounts. If you try to fix it without understanding what happened, you could lose some bitcoins.
Yeah this is what I am worried about. But isn't it strange this such basic feature is not easily available in program? Or people only install it on one PC throughout their life?