Same Effect More than Once in Different Strengths: In cases when twoor more identical spells are operating in the same area or on thesame target, but at different strengths, only the best one applies. Forexample, if a character takes a –4 penalty to Strength from a ray ofenfeeblement spell and then receives a second ray of enfeeblement spellthat applies a –6 penalty, he or she takes only the –6 penalty. Bothspells are still operating on the character, however. If one ray ofenfeeblement spell is dispelled or its duration runs out, the other spellremains in effect, assuming that its duration has not yet expired.
To help answer my own question, let me quote the PHBQuote from: PHB-172Same Effect More than Once in Different Strengths: In cases when twoor more identical spells are operating in the same area or on thesame target, but at different strengths, only the best one applies. Forexample, if a character takes a –4 penalty to Strength from a ray ofenfeeblement spell and then receives a second ray of enfeeblement spellthat applies a –6 penalty, he or she takes only the –6 penalty. Bothspells are still operating on the character, however. If one ray ofenfeeblement spell is dispelled or its duration runs out, the other spellremains in effect, assuming that its duration has not yet expired.