When data is entered into a memory location where there is already data, the new data will erase the original data. Most memory locations are meant to handle one input of data. If you try to add more data, you’ll end up erasing the original data. If you need both sets of data, find a memory location that you can override without losing crucial data (such as some tangential data that is no longer relevant to anything).
However, depending on what software and other programs you’re using, it could change the address of the memory location. This is unlikely, but since I’ve never dealt with this, I wouldn’t know first hand. So, take my answer lightly, because I could be completely wrong.