I just did RDLs after my DLs in yesterday's workout, and the only problem I encounter is I'm pretty fatigued from the DLs, so my strength is down on the RDLs and I'm a little shaky. I primarily wanted the hamstring stretch, so I wasn't that concerned. Normally, I would do one or the other (or GMs) - I wouldn't do them both in the same workout. I'm using lighter RDLs and GMs to help with my hamstring flexibility so I don't have to spend as much time stretching (getting lazy in my old age).
You can also try GMs (Good Mornings), DB leg curls, and Glute/Ham Raises. There have been videos posted of all these exercises. I also prefer the Romanian DL (RDL) over the SLDL - the lower back is less involved and they really just focus on glute/hamstring.