All mine have orange tops, always have in the recent past... I would look at the actually casettes - the plastic container is of litle consequence. If I had to guess, I would say they just ran out of orange lids, or are in the process of no longer using various colours (which I believe I Heard something about), and you simply have one of the old, one of the new. I would not worry too much about it.
I noticed this months ago with Pan F with a grey top (should be orange), FP4+ with a grey top (should be blue) and HP5 with a black top (should be green). It is a bloody nuisance trying to find the right roll in a camera bag when they all have the same colour top. So I asked Simon Galley about it and basically coloured tops are not a priority for Ilford any more due to the amount they would have to order. So save those you have.
<edit> See page 9 of (there was a url link here which no longer exists) for my question and Simon's reply on the subject of caps.
I bought about 100 rolls of 35mm HP5+ and some had green tops and some had black. I've been keeping all of my colored caps because it makes it so easy to grab the right film.
From a business stand point, I understand why they ditched this.
You can buy a supply of brightly colored little round labels at office supply stores, not expensive, to do your own color coding. Small inconvenience, but much preferable to not having the product.
You can buy a supply of brightly colored little round labels at office supply stores, not expensive, to do your own color coding. Small inconvenience, but much preferable to not having the product.
I bulk load my 35mm film, and I use coding scheme based on colored plastic tape. Since I only use one film (TMY), the coding has to do with whether the film has been exposed. When I first load the film, I put the cassette into the plastic canister, attach the lid, and then put a strip of tape across the top and down the side. Then, when I take the film out of the camera after it has been exposed, I wrap the tape around the circumference of the canister. That way I know which films have been exposed and which have not.
I also like to trim off the leader after taking the exposed film out of the canister, and use the scissors on my Swiss army knife to cut off the leader. Unfortunately, I can't carry the knife on a plane, so that isn't possible when traveling.