Well,

da/de means too, as well. So far so good.

When you make use of it after v+ip, what you mean by that is what you mean with the one without "da/de" is another possibility (among others) for something (you need a context to know the other possibilities/options).

Hmmm...

You mean something like gidip bir daha gelmemek ihtimali de var  -  ´yes it is an option among other options´. Kind of picking up one of the possibilities.

Well,

That´s fine but I think I have a better explaination now.

Most of the times, there is no difference in meaning as pointed out by gokuyum with/without "da"/"de".

x-ip y = doing x and y

x-ip de y = doing x and then y or doing y after x

gidip geldim = I went (there) and came (back)

gidip de geldim = I went (there) and then came (back); I came (back) after going (there)

And also; the title is wrong. It´s not -ip + locative case suffix but "da"/"de" which is written separately.

Yes, it turned out wrong. But I had some doubts while typing it, that´s why I added the question mark.

V1-ip V2 is a very tight package I see. The V´s are almost seen as one action. de/da in the middle may bring a slight breeze of air between them.