this is btc from mybitcoin
It could be, but several of the people who have sent BTC to addresses for their mybitcoin accounts have noted that the funds have not been moved from those addresses.
How would they know this if we don't need to use the same address to send coins? Or are all transactions trackable because it's actually Address A (original receiving address) -> Address B (New sending adress), then Address B -> Address C (consolidating address) ?