The second "explosion" was probably the good cell set off by heat from the first cell to fail. The CR123 cells have a flammable electrolyte. With two cells, one is close to the limit allowed for transportation on passenger aircraft by UN and DOT regulations (although it is allowed since they are in an apparatus). There is a lot of energy there that can cause a problem when something goes wrong.

Chinese Li-MnO2 (CR123) and Li-FeS2 (similar to Eveready L91) are generally not as safe as Japanese or American made cells. (The Chinese cells are improving, so don't think they won't be as good in a few years.) They use different electrolytes and lack some features. It should be noted that most "American" made CR123 cells are made in Japan, or in a Japanese designed plant, and wrapped with the US manufacturer's label. The Japanese Li cells and Eveready L91 and L92 cells are a fine product that can be trusted. However, Eveready alkaline cells have a tendance to leak due to a poor crimp seal design. Duracell has a better seal design. I have had less experience with RayOVac alkaline cells, but all experience to date has been favorable.

Button cells have much less energy, so failure is not as dramatic. Because the cell case cannot take much pressure without deforming, poor electrolytes or internal problems are readily observable. Considering all the button cells in watches, with very few problems, one can be confident in button cells. Again, most are made in Japan, often packaged with a US manufactuer's name. Japan really knows how to make a quality product.

Finally, I agree that one should not look to save money on batteries by buying cheap, unless it is cheaper because of buying in bulk. There is a lot of energy in cells that can cause problems if released as heat rather than electrical work. One carries the weight of batteries because they are needed, so spend a little more and buy quality.

Spud