Opening two of the same wallet (tested in v0.18.0 of bitcoin-qt 64 bit) will cause a database collision, and will crash the program.

`[marshall@likon] {21:21} [~] $ bitcoin-0.18.0/bin/bitcoin-qt `
`terminate called after throwing an instance of 'std::runtime_error'  what():  BerkeleyBatch: Can't open database 8204388-wallet.dat (duplicates fileid 8b1c090000000800e25686350000000000000000 from 1352491-wallet.dat)`
`Aborted (core dumped)`

I have been able to reproduce the issue by importing two of the same wallet (with different filenames).
{
    for (const std::string& walletFile : wallet_files) {
        std::string error;
        std::vector<std::string> warnings;
        std::shared_ptr<CWallet> pwallet = CWallet::CreateWalletFromFile(chain, WalletLocation(walletFile), error, warnings);
        if (!warnings.empty()) chain.initWarning(Join(warnings, "\n"));
        if (!pwallet) {
            chain.initError(error);
            return false;
        }
        AddWallet(pwallet);
    }
    return true;
}
void StartWallets(CScheduler& scheduler)
{
    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
        pwallet->postInitProcess();
    }
    
    scheduler.scheduleEvery(MaybeCompactWalletDB, std::chrono::milliseconds{500});
    scheduler.scheduleEvery(MaybeResendWalletTxs, std::chrono::milliseconds{1000});
}
void FlushWallets()