Comparing 2 Dictionary Instances

var contentsEqual = source.DictionaryEqual(target);

// ...

public static bool DictionaryEqual<TKey, TValue>(
    this IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second)
{
    return first.DictionaryEqual(second, null);
}

public static bool DictionaryEqual<TKey, TValue>(
    this IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second,
    IEqualityComparer<TValue> valueComparer)
{
    if (first == second) return true;
    if ((first == null) || (second == null)) return false;
    if (first.Count != second.Count) return false;

    valueComparer = valueComparer ?? EqualityComparer<TValue>.Default;

    foreach (var kvp in first)
    {
        TValue secondValue;
        if (!second.TryGetValue(kvp.Key, out secondValue)) return false;
        if (!valueComparer.Equals(kvp.Value, secondValue)) return false;
    }
    return true;
}