Adding a Second adervirtising for a product can increase the impression?

adding a Second AD for a product can increase the impression ?
or i don’t need to add second AD , it is enough to set daily budget higher on first AD for product ?

Set daily budget higher if you are breaching it. Otherwise makes no difference. If its 5 pounds or 10 pounds but you are only getting 1 pound in clicks it won’t change anything.

Can have the same product in multiple campaigns, no clue if you get more ads shown of that type or just the ad slots you get being the same but split between campaigns.

If not getting enough clicks you may want to re-examine the campaign. Drop words not getting clicks, perhaps even blacklist them.
Ideally go for sales over impressions or clicks. Over time adjust the keywords such that the ones that merely charge a click but get no sales is dropped while new keywords are tried. The campaign report can help figure out things.