As you said, دوست دارم has 2 pronunciations. If someone write it, you should guess which meaning they are referring to according to the context. But if someone tell it to you, you can simply get the meaning by the way they pronounce it. دوسِت دارم = I love/like you. دوست دارم = I like (something).

دوستت دارم (I love/like you) when written the way it is pronounced in conversation, it would be: دوست دارم. And the conversational spelling of دوست دارم (I like...) can also be written as دوس دارم very informally. It's not common though. But if you doubt about which way the writer has written you can only guess the meaning from the context.

I think you mean ...دوست دارم as "I like..." and دوسِت دارم as "I love you/ I like you" the first one is a compound verb in first person singular, example: مدل جدید موهات رو دوست دارم I like your new haircut the second one is the contraction of دوستَت دارم there is no way to find out if he/she means "I like you" or "I love you", only his/her actions would tell :)

I think you wanted to say that the phrase "دوست دارم" has 2 different meaning but it is the same in writing, and you have to guess the exact meaning of that in a text. But notice that it is strongly recommended that you write "دوستت دارم" for "I like/love you", and write "دوست دارم" for "I like" in writing. Hope this helps.

If you want to find different ways to say 'I like you or I love you" you can say: I like you =دوستت دارم I love you= عاشقتم or to show that in writing you can just Emphasis by using خیلی خیلی دوست دارم