But every time we can't get same namespace

It doesn't make sense for the namespace to change. The prefix can change, but it doesn't matter what prefix the XML uses. The one you use doesn't have to be the same. Just the namespace has to be the same.

But let's say that's what you have. If you need to match nodes by name no matter which namespace the element belongs to, you can use

.../name()="name"/...
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instead of

.../ns:name/...
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