`bitcoin.conf`:
```
...
testnet=1
# [wallets]
test.wallet=test_alpha
test.wallet=alpha_wallet
test.wallet=none
...
```

Run bitcoin client.

`debug.log`:
```
...
2019-02-03T13:09:23Z Using wallet directory /home/hebasto/.bitcoin/testnet3/wallets
2019-02-03T13:09:23Z init message: Verifying wallet(s)...
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/test_alpha/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/test_alpha/db.log
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/alpha_wallet/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/alpha_wallet/db.log
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/none/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/none/db.log9
...
```

In multi-wallet environment a wallet database file reference (`wallet.dat`) without a wallet name (e.g., `test_alpha`) could be confusing.
#include <wallet/db.h>
#include <addrman.h>
#include <hash.h>
#include <protocol.h>
#include <util/strencodings.h>
#include <wallet/walletutil.h>
#include <stdint.h>
#ifndef WIN32
#include <sys/stat.h>
#endif
#include <boost/thread.hpp>
namespace {
void CheckUniqueFileid(const BerkeleyEnvironment& env, const std::string& filename, Db& db, WalletDatabaseFileId& fileid)