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).
{
    if (IsImmatureCoinBase() && IsInMainChain()) {
        return GetCachableAmount(IMMATURE_CREDIT, ISMINE_WATCH_ONLY, !fUseCache);
    }
    return 0;
}
CAmount CWalletTx::GetChange() const
{
    if (fChangeCached)
        return nChangeCached;
    nChangeCached = pwallet->GetChange(*tx);
    fChangeCached = true;
    return nChangeCached;
}
bool CWalletTx::InMempool() const
{
    return fInMempool;
}
bool CWalletTx::IsTrusted(interfaces::Chain::Lock& locked_chain) const
{
    std::set<uint256> s;
    return IsTrusted(locked_chain, s);
}
bool CWalletTx::IsTrusted(interfaces::Chain::Lock& locked_chain, std::set<uint256>& trusted_parents) const