Bi-directional Dictionary with constructors to help out with initialization

BiDictionary.cs

public class BiDictionary<TFirst, TSecond>
{
    private readonly IDictionary<TFirst, TSecond> firstToSecond;

    private readonly IDictionary<TSecond, TFirst> secondToFirst;

    public BiDictionary()
    {
        firstToSecond = new Dictionary<TFirst, TSecond>();
        secondToFirst = new Dictionary<TSecond, TFirst>();
    }

    public BiDictionary(
        ICollection<KeyValuePair<TFirst, TSecond>> collection,
        IEqualityComparer<TFirst> firstComparer = null,
        IEqualityComparer<TSecond> secondComparer = null)
    {
        firstComparer = firstComparer ?? EqualityComparer<TFirst>.Default;
        secondComparer = secondComparer ?? EqualityComparer<TSecond>.Default;

        this.firstToSecond = new Dictionary<TFirst, TSecond>(collection.Count, firstComparer);
        this.secondToFirst = new Dictionary<TSecond, TFirst>(collection.Count, secondComparer);

        foreach (var item in collection)
        {
            this.firstToSecond.Add(item.Key, item.Value);
            this.secondToFirst.Add(item.Value, item.Key);
        }
    }

    public void Add(TFirst first, TSecond second)
    {
        if (firstToSecond.ContainsKey(first) || secondToFirst.ContainsKey(second))
        {
            throw new ArgumentException("Duplicate first or second");
        }
        firstToSecond.Add(first, second);
        secondToFirst.Add(second, first);
    }

    public bool TryGetByFirst(TFirst first, out TSecond second)
    {
        return firstToSecond.TryGetValue(first, out second);
    }

    public bool TryGetBySecond(TSecond second, out TFirst first)
    {
        return secondToFirst.TryGetValue(second, out first);
    }
}