According to certain aspect, the present invention provides a two-bottle package design comprising a first bottle and a second bottle. The second bottle can be frictionally inserted into an opening in the middle of the first bottle during normal storage and separated from the first bottle for mixing before actual application of the stored products. In one embodiment, the package comprises a first bottle to contain a liquid product and the second bottle to contain a concentrate refill of the first product. In another embodiment, the package comprises a first bottle to contain the first product, and a second bottle to contain a second product to be mixed with the first product before actual application of the mixture.